bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-course of enzyme adaptation. I. Effects of substituting dietary glucose and fructose at constant concentrations of dietary protein
Authors: Szepesi B. , Freedland R. A.
Published: December 2009

The effect of dietary fructose on liver, kidney, and adrenal enzymes was studied in male Sprague–Dawley rats. Dietary fructose increased relative liver and kidney sizes, liver glycogen, and liver protein. The percentage increases in relative liver and kidney sizes were independent of dietary protein, but relative liver sizes were smaller in the absence of protein.The activities of all the liver enzymes studied, except glucokinase, were increased by a 65% fructose diet containing 25% casein. The rates of increases differed between enzymes; the activities of L-α-glycerophosphate dehydrogenase and phosphoenolpyruvate carboxykinase (PEP-carboxykinase) reached almost maximum in 1 day, glucose 6-phosphatase, 6-phosphogluconate dehydrogenase, and pyruvate kinase activities reached maximum in about 2 days, and glucose 6-phosphate dehydrogenase, malic enzyme, dihydroxyacetone kinase, phosphofructose kinase, and phosphohexose isomerase required at least 3 days to reach maximum activity after the dietary change. The increases in the activities of liver fructose 1,6-diphosphatase, glucose 6-phosphate dehydrogenase, pyruvate kinase, and phosphohexose isomerase did not occur in the absence of dietary protein. The activities of liver phosphofructokinase and malic enzyme were increased equally well whether the fructose diet contained protein or not, while the increases in the activities of other enzymes were less in the absence of dietary protein.The half-life of liver malic enzyme was estimated as 3 days in the glucose to fructose dietary change and 1 day in the fructose to glucose dietary change. Since malic enzyme activity was increased by fructose feeding about threefold, the data suggest that under the conditions of the experiment fructose increased malic enzyme activity by decreasing the rate of breakdown of the enzyme.In general, kidney enzymes were affected by fructose to a lesser extent than the corresponding enzymes in liver. This was particularly significant in the case of kidney glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malic enzyme, the activities of which were only slightly increased in kidney. The activities of these three enzymes in the adrenal glands were not increased by fructose feeding.
The outer layer of the cell envelope of Halobacterium halobium
Authors: Marshall Carolyn L. , Wicken A. J. , Brown A. D.
Published: December 2009

The outer layer of the cell envelope of Halobacterium halobium was isolated after suspending the envelope in either 1 M NaCl or 0.02 M MgCl2. Chemical analysis of the isolated, solubilized outer layer showed it to consist of protein or glycoprotein with about 3% RNA. No free or bound lipid was detected. No cytochromes were present in the outer layer. Components commonly associated with bacterial cell walls were absent.Chemical composition together with the marked instability of the outer layer in a slight ion deficit are not consistent with a function of this layer as a "cell wall" of the organism.
Alternative mechanism for a bimolecular nonsequential enzymic reaction
Authors: Hurst R. O.
Published: December 2009

An enzymic reaction mechanism characterized as 'di-Uni Iso Ping Pong' which has the same product inhibition pattern as the 'Ping Pong Bi Bi' mechanism but a different order for the release of products is discussed. A basis for differentiating the two mechanisms by dead-end inhibition studies is given.
The purification and properties of an amino acid arylamidase from bovine milk
Authors: Mellors A.
Published: December 2009

An amino acid arylamidase is present in bovine milk and is associated with the "microsomes" of the milk-fat globule membrane. It has been purified by DEAE-cellulose chromatography of a 0.1 M NaCl extrast of milk microsomes. The specific activity of the purified arylamidase was increased 12 700-fold over that of the milk. Three peaks of arylamidase activity could be recognized after the chromatography. One form was apparently bound to casein. The major peak of arylamidase activity hydrolyzes lysyl-, alanyl-, valyl-, and arginyl-β-naphthylamides at similar rates, with little activity against glycyl- and histidyl-β-naphthylamides. The arylamidase requires the restoration of sulfhydryl groups by dithiothreitol for maximum activity. It is inhibited by EDTA and some divalent metal ions, and only calcium ions restore the EDTA-inactivated enzyme. The optimum pH for the hydrolysis of lysyl-β-naphthylamide is pH 7.7, and high concentrations of this substrate are inhibitory.
De novo biosynthesis of inosinic and uridylic acids by salmon testes and liver
Authors: Tarr H. L. A.
Published: December 2009

Salmonid fish liver homogenates and immature testes slices when incubated 4 or 5 h at 25° or 20 h at 5° in a medium containing inorganic salts, radioactive substrates, and intermediates usually associated with recognized enzymic pathways of the de novo biosynthesis of purine and pyrimidine rings formed radioactive uridylic acid and inosinic acid. These were largely degraded by the tissue preparations to uracil and hypoxanthine which were purified for chemical studies. Degradation of hypoxanthine formed in this manner showed that C-6 was formed from radioactive carbonate and C-4 and C-5 from radioactive glycine. Degradation of uracil showed that metabolism of radioactive carbonate did not result in exclusive labeling of C-2 of uracil, but also caused more or less extensive labeling of the C-4, C-5, and C-6 fraction, especially with liver preparations. L-Aspartate was incorporated almost exclusively into the C-4, C-5, and C-6 fraction of uracil, but not into hypoxanthine.
Effect of age on protein and ribonucleic acid metabolism in mouse skeletal muscle
Authors: Srivastava Uma , Chaudhary K. D.
Published: December 2009

Protein content, RNA concentration, in vivo and in vitro incorporation of L-leucine-14C (U.L.) into protein and of uridine-2-14C into RNA of the homogenate, and various fractions of muscle of mice were measured at various ages. Protein content showed a continuous increase in the homogenate, nuclei–myofibrillar, and soluble fraction of the muscle of mice undergoing development. Maximum increase was noted in the soluble fraction. RNA content dropped rapidly in the homogenate and in all subcellular fractions of the muscle up to 30 days, followed by a slow decline. Ratio of DNA as well as RNA content to protein decreased continuously in the homogenate and in all subcellular fractions with aging.In vivo incorporation of L-leucine-14C (U.L.) into protein of the homogenate and various subcellular fractions of the muscle decreased with the increasing age of the animal. In vitro incorporation of labelled leucine into protein by the cell-free preparation of skeletal muscle also decreased with aging. Such a decrease in the incorporation was thought to be due to decrease in the content of polysomes in the aging muscle.In vivo incorporation of uridine-2-14C into RNA of the homogenate and subcellular fractions of muscle showed a decrease with age. Similar types of results were obtained in studies in vitro.
Release of intracellular enzymes into serum
Authors: Wells Ibert C.
Published: December 2009

Serum lactic acid dehydrogenase (LDH) activity of normal rabbits is increased after intramuscular injections of peanut oil suspensions of dialyzable saline extracts of heart, kidney, liver, or lung tissue from normal rabbits, and after injections of histamine. Activity is maximal by 24 h and normal by 48 h after injection. The LDH isoenzyme patterns of the sera obtained after the administration of the tissue extracts differ markedly from each other and from the LDH isoenzyme patterns of the tissues extracted. They also differ from the serum LDH isoenzyme patterns obtained after the administration of histamine. These results suggest that histamine is not the active substance present in the tissue extracts, that the active materials in the tissue extracts are different from each other, and that the tissue extracts probably do not effect the release of LDH from the kind of tissue used in their preparation. The active substances in the tissue extracts differ in their heat stabilities, are stable when lyophilized, and are adsorbed by Dowex 1 (Cl−) but not by Dowex 50 (H+). These findings suggest that cells contain low molecular weight substances which have the potential of releasing LDH, and presumably other proteins also, from the cells of other tissues.
Proflavine and fidelity of DNA polymerase
Authors: McCarter J. A. , Kadohama N. , Tsiapalis C.
Published: December 2009

With native calf thymus DNA3 as primer and DNA polymerase of E. coli, proflavine (0 × −1 × 10−4 M) inhibited the incorporation of dATP, dCTP, dGTP, and TTP about equally. Using dAT as primer there was inhibition of the rate of synthesis of polynucleotide by proflavine and no more incorporation from dGTP and dCTP than in the absence of the acridine. Nearest-neighbor analysis of the polynucleotide synthesized by DNA polymerase from dATP and TTP showed that sequences of TpT and ApA were formed in the presence of proflavine. Changed sequences were observed whether the reaction was primed with dAT or was unprimed, and the extent of change depended on the concentration of proflavine. The homopolymer dA:dT was identified as one of the products formed.
Occurrence of octadeca-trans-2,cis-9,cis-12-trienoic acid in pollen attractive to the honey bee
Authors: Hopkins C. Y. , Jevans A. W. , Boch R.
Published: December 2009

Mixed pollen, gathered by honey bees, contained a free fatty acid which was isolated and identified as octadeca-trans-2,cis-9,cis-12-trienoic acid. The acid was shown to be an attractant for the honey bee. It is evidently produced by the plant and acts as a food marker for the insect.
Effects of aldosterone on the incorporation of 32P into the nucleotides of heart muscle
Authors: Liew C. C. , Gornall A. G.
Published: December 2009

A subcutaneous injection of aldosterone into normal rats (2 μg/100 g body weight) increased the incorporation of inorganic phosphate (32P) during 1 h into the ADP, ATP, and RNA fractions of heart muscle. Similar effects were noted using adrenalectomized rats. Neither hydrocortisone (150 μg/100 g body weight) nor desoxycorticosterone acetate (250 μg/100 g body weight) showed this effect in normal rats.An aldosterone effect was also observed in vitro using 2 ng (5.6 × 10−9 M) per milliliter of centrifuged rat heart homogenate. In the absence of exogenous substrate, there was an increased incorporation of 32P into the ATP fraction but not into the RNA fraction. In the presence of pyruvate the radioactivity of both ATP and RNA was enhanced by aldosterone during a 1-h incubation. It is suggested that the action of aldosterone on energy metabolism in heart muscle precedes RNA synthesis.
Multiple molecular forms of avian aldolases. II. Enzymic properties and amino acid composition of chicken (Gattus domesticus) breast muscle aldolase
Authors: Marquardt Ronald R.
Published: December 2009

Several properties of crystalline chicken (Gallus domesticus) breast muscle aldolase (fructose 1,6-diphosphate–D-glyceraldehyde 3-phosphate lyase, EC 4.1.2.13) were determined. The enzyme was found to have a broad pH optimum centered around pH 7.1 and to be remarkably stable over a wide pH range. The temperature coefficient Q10 is 2.6 in the range from 10 to 35 °C. The enzyme is stable at 48 °C for 10 min and almost completely inactivated at 55 °C. The apparent Michaelis constants for fructose 1,6-diphosphate and fructose 1-phosphate were 4.2 × 10−5 M and 1.7 × 10−2 M, respectively. The phosphate inhibitor constant (K1) was 5.5 × 10−3 M.Chicken breast muscle aldolase is similar to the rabbit enzyme in many of the above properties, although there are significant differences in heat stability and amino acid composition.
Studies on the hemoglobin of the great horned owl (Bubo virginianus)
Authors: Abercrombie C. , Maber B. R. , Vella F.
Published: December 2009

Hemoglobins of 24 adult great horned owls (Bubo virginianus) were found to be identical on the basis of electrophoretic (using filter paper and agar and starch gels in various continuous and discontinuous buffer systems), alkali resistance, and spectral absorption properties. Peptide maps of tryptic and chymotryptic digests of globin from two specimens were compared with similarly produced maps of globin from human hemoglobin A1. Similarity in position on the map and in specific staining properties of several spots indicated that a number of presumably homologous sequences occur in both these globins. These studies indicate that in this species of owl the adult globin contains two different polypeptide chains (α and β), of which one also occurs in fetal globin (α and γ), and that the β chains in this species and in man are more dissimilar than the α chains of the same two species.
Mode of action of choline. III. Metabolism of nonessential fatty acids in choline-deficient rats
Authors: Chalvardjian A.
Published: December 2009

To investigate the increase in ratio of C16 to C18 nonessential fatty acids in hepatic triglycerides of choline-deficient rats, two groups of rats fed, respectively, a choline-deficient and a choline-supplemented diet for 3–4 days were injected either with 1-14C-acetate intraperitoneally or with a mixture of 9,10-3H-palmitate and 18-14C-stearate intravenously. The choline-deficient and choline-supplemented rats were killed 3 h after labelled acetate injection. Further groups of choline-deficient and choline-supplemented rats were killed at intervals of 1 min to 6 h after injection with labelled palmitate and stearate. Extracts of lipids from livers and sera were analyzed by gas–liquid and thin-layer chromatography. In the choline-deficient rats injected with 1-14C-acetate the ratio of C16 to C18 labelled fatty acids incorporated into hepatic and serum triglycerides was increased and the ratio of those incorporated into hepatic and serum phospholipids was decreased. The ratio of monounsaturated fatty acids to saturated fatty acids incorporated into the triglycerides and phospholipids of liver and serum of the choline-deficient rats was decreased compared to that of the choline-supplemented rats. Similar differences between the two groups of rats were evident in the hepatic lipids of animals injected with 3H-palmitate and 14C-stearate. The early alteration of the ratios of hepatic nonessential fatty acids suggests that the initial change is a decreased desaturation of fatty acids.
Automated chromatographic analysis of free monosubstituted guanidines in physiological fluids
Authors: Durzan D. J.
Published: December 2009

An automated analytical method for the quantitative determination of monosubstituted guanidines in the physiological fluids of plants and insects is described with special reference to conifers and spruce budworm larvae. Over 25 monosubstituted guanidines of known structure can be separated on columns of an amino acid analyzer of the Spackman, Stein, and Moore type, and determined by the Sakaguchi reagent as modified by Satake and Luck. The automated method minimizes the problem of color decay of the reaction product of the guanidine derivative with the Sakaguchi reagent and reveals the occurrence of several yet unidentified guanidines.
The kinetics of inactivation of adenylosuccinate lyase: evidence for a substrate-induced conformational change
Authors: Bridger W. A. , Cohen L. H.
Published: December 2009

The kinetics of inactivation of adenylosuccinate lyase by the alkylating agents N-ethyl maleimide and iodoacetamide and by photooxidation have been investigated. The inactivation by the alkylating agents indicates that there are several groups on the enzyme whose reaction affects activity. The presence of AMP, a product of the enzymic reaction, decreases the rate of inactivation by both N-ethyl maleimide and iodoacetamide, while the other product, fumarate, has no effect on the rate. In the case of photoinactivation, the rate is accelerated by the presence of AMP. Fumarate, which again has no effect by itself, causes an overall protection of the enzyme from photoinactivation when added in the presence of AMP. The results, suggesting that fumarate is unable to combine with the free enzyme but does combine with the enzyme–AMP complex, are consistent with the strongly preferred sequence of product release determined by a previous initial-rate kinetic study. Both the kinetics of inactivation and the initial-rate kinetics may be interpreted in terms of a mechanism involving the operation of an enzymic conformational change which is allowed only when either AMP or adenylosuccinate is bound to the enzyme.
A micro-method for the quantitative determination of deoxyrihonuclease
Authors: Jarvis Audrey W. , Lawrence R. C.
Published: December 2009

A diffusion slide assay using a thin layer of deoxyribonucleic acid agar has been developed as a micro-method for the quantitative study of deoxyribonculease. Concentrations of deoxyribonuclease down to 0.005 μg/ml can be measured with high reproducibility. The enzyme needs no prior purification and small quantities only are required for each test. The method is particularly suitable for the measurement of large numbers of samples.
Stability of induced α-glucosidase activity in the absence of inducer
Authors: Bell Robert G.
Published: December 2009

Yeast cells containing induced α-glucosidase activity lose 10% of the original activity per hour when placed in phosphate buffer – glucose medium. The presence of inducer has no effect on the rate of loss. Induced cells placed in complex medium plus glucose or glycerol show an initial rise in α-glucosidase activity, and then a slow decrease which is accelerated when growth stops. The loss of induced enzyme activity in buffer–glucose medium is inhibited by inhibitors of energy production or protein synthesis whether they are added immediately or 2 or 4 h after suspension of cells in the medium. The ability of the inhibitors to block the loss of induced enzyme activity is correlated with their ability to inhibit protein synthesis. Ammonium sulfate inhibits the loss of α-glucosidase activity after a lag but amino acid or purine–pyrimidine mixtures do not. The loss of induced enzyme activity in cell-free supernatant solutions is less than 2% of the original activity per hour at 30°.
The quantitation of pheophorbide a, pyropheophorbide a, and their esters
Authors: Roberts D. W. A.
Published: December 2009

The molar extinction coefficients of pheophorbide a, methyl pheophorbide a, and pheophytin a are identical within experimental error. A similar situation holds for pyropheophorbide a and its methyl ester.Pheophorbide a and pyropheophorbide a are adsorbed on glass from solution in ether and chloroform but not from solution in acetone or dioxane.It is recommended acetone be used as the solvent for the quantitation of pheophorbide a and pyropheophorbide a.
Deoxyrihonucleates of crabs of the superfamily Brachyrhyncha
Authors: Klett Robert P. , Chabot Irene M. , Smith Michael , Hart Josephine F. L.
Published: December 2009

The deoxyribonucleates have been characterized from six species of crab representing four families of the Brachyuran superfamily Brachyrhyncha. Five of the species contain two components related to the two (density about 1.680 and 1.700 g/ml in aqueous cesium chloride) which have previously been found in species of the genus Cancer. These and other results show that in the superfamily Brachyrhyncha, five families (Atelecyclidae, Cancridae, Gecarcinidae, Grapsidae, and Pinnotheridae) contain the two types of deoxyribonucleate and two families (Portunidae and Xanthidae) appear to contain only the more dense type of deoxyribonucleate.
The release of nucleic acids and protein from ascites tumor cells incubated with glycerol, dimethylsulfoxide, and inositol
Authors: Eng C. P. , Morgan J. F.
Published: December 2009

The effect of the cryoprotective agents glycerol, dimethyl sulfoxide (DMSO), and inositol was studied on Ehrlich and 6C3HED mouse ascites tumor cells. A marked release of both nucleic acids and protein was caused by incubation for 1 h in glycerol or DMSO, an observation which suggested cell disruption. The osmolarity of ascites tumor fluid was found to be 300 ± 10 milliosmoles, a level corresponding to 2.1% DMSO, 2.2% glycerol, and 5.4% inositol. Incubation in isotonic solutions of DMSO and glycerol caused a marked release of both nucleic acids and protein. In contrast, incubation with isotonic inositol caused a release of nucleic acids but essentially no protein beyond the amount released in the control fluid of Hanks' balanced salt solution. In all cases, the release of intracellular materials was influenced by age of the tumor cells and the temperature of incubation.The specific release of nucleic acids in the presence of inositol was found to occur to greatest extent early in the incubation period. This release could be inhibited by sodium chloride.
Intestinal absorption of heparin
Authors: Koh T. Y.
Published: December 2009

Dimethylsulfoxide and diethylsulfone, and their homologues, induced the absorption of heparin from the rabbit intestine.Using the criterion of prolongation of whole blood clotting time, it was found that the quantitative absorption of heparin, as induced by di-n-propylsulfoxide or di-n-propylsulfone, increased with increasing amount of sodium heparinate administered to the intestine.
3-Deoxy-D-gluco-octulosonic acid
Authors: Williams D. T. , Perry M. B.
Published: December 2009

3-Deoxy-D-gluco-octulosonic acid was prepared by oxidation of 3-deoxy-D-glycero-D-gulo-octonic acid and 3-deoxy-D-glycero-D-ido-octonic acid made by the action of sodium cyanide on 2-deoxy-D-gluco-heptose. Gas chromatographic procedures for the detection of 3-deoxy-D-gluco-octulosonic acid are described.
Effect of yohimbine on 14CO2 production from 14C-pyrrole-ring-labeIed DL-tryptophan in rats treated with L-tryptophan, DL-α-methyltryptophan, and Cortisol
Authors: Sourkes Theodore L. , Missala Krystyna
Published: December 2009

Yohimbine, previously shown to inhibit tryptophan pyrrolase in vitro and in vivo, was tested in rats whose pyrrolase activity had been elevated by prior treatment with cortisol, tryptophan, or α-methyltryptophan. The alkaloid exerted an inhibitory effect on the oxidation of tryptophan-2-(pyrrole ring)-14C in rats given Cortisol or α-methyltryptophan, but had no effect on those given tryptophan loads. Consideration of the respective modes of action of the three stimulators of tryptophan pyrrolase activity and the observed results suggests that yohimbine acts at the stage of reduction of holoenzyme to its active form, a process requiring L-tryptophan.The oxidation of 14C-tryptophan in vivo seems to involve a progressive increase in the activity of pyrrolase during the first 1–1.5 h. By prior treatment of rats with tryptophan loads, the oxidation approaches a linear, but submaximal, rate during this period. The size of the air-pool in the metabolic cages (dead space) does not introduce, within the limits studied, an artifact into the measurements of the rate of tryptophan oxidation in vivo.
Extracellular polysaccharides from suspension-cultured sycamore cells
Authors: Aspinall G. O. , Molloy J. A. , Craig J. W. T.
Published: December 2009

Three polysaccharides have been isolated from the culture medium of suspension-cultured sycamore cells (Acer pseudoplatanus L.). A pectinic acid which contains 67% of galacturonic acid residues has been shown to have features in common with other pectins, with arabinose, galactose, and rhamnose as constituent sugars. Methylation and partial hydrolysis have indicated that the arabinogalactan is similar to those from coniferous woods in containing a highly branched framework of D-galactopyranose residues mutually joined by (1 → 3) and (1 → 6) linkages with the majority of side chains terminated by L-arabinofuranose residues. A fucoxyloglucan has been shown by methylation and enzymic hydrolysis to possess a structure similar to those of the so-called seed 'amyloids' with a cellulose-like (1 → 4)-linked β-D-glucan chain with side chains terminated by L-fucopyranose and D-xylopyranose residues.
The production of α-hydroxyglutaric acid from glutamic acid by cell-free preparations of Peptococcus aerogenes
Authors: Johnson W. M. , Westlake D. W. S.
Published: December 2009

Active cell-free extracts of Peptococcus aerogenes were prepared which metabolized glutamic acid to α-hydroxyglutaric acid. Factors affecting the formation of this intermediate were studied by following the conversion of glutamic acid labelled with 14C in the one or five positions. The results of these experiments revealed that the production of α-hydroxyglutaric acid from glutamic acid by cell-free extracts was NAD-dependent. The labelled α-hydroxyglutaric acid produced by NAD-supplemented extracts was purified by anion exchange chromatography and identified by several methods including paper and thin-layer chromatography, mass spectrometry, and infrared spectroscopy. A pathway has been proposed for the conversion of glutamic acid to α-hydroxyglutaric acid by cell-free extracts of P. aerogenes.
The influence of haptoglobin on the reactivity of the –SH groups of hemoglobin
Authors: Malchy B. , Dixon G. H.
Published: December 2009

The rate of reaction of the β93 sulfhydryl of hemoglobin with iodoacetamide and 2,2′-, and 4,4′- dithiodipyridine is much slower when the hemoglobin is bound by haptoglobin than when it is free. However, these sulfhydryl reagents will react with the haemoglobin–haptoglobin complex, and the reaction of the complex with iodoacetamide is still at position β93. The results suggest that haptoglobin might induce a conformation change on oxyhemoglobin which is similar to that occurring upon deoxygenation.
Gene action in the human haptoglobins. IV. Amino acid sequence studies on the haptoglobin α chains
Authors: Black J. A. , Dixon G. H.
Published: December 2009

Alpha chains of human haptoglobin have been prepared from whole haptoglobin of genetic type Hp 2–1 purified from the ascites fluid of a single patient. Amino acid sequence analysis has been carried out on these light chains which represent the products α1S and α2(F,S) of the single genes Hp1S and Hp2(F,S), and are, respectively, 83 and 142 residues in length. The data reported here concern the sequence analysis of two series of tryptic peptides, one obtained by unlimited cleavage of the chains by p-toluene sulfonamido-phenylethyl chloromethyl ketone - trypsin, and the second following limitation of trypsin cleavage to arginyl residues after modification of lysyl residues by trifluoracetylation. The major technique for sequence analysis of these peptides was a modification of the p-dimethylaminonaphthalene-sulfonyl-Edman (dansyl-Edman) procedure employing a new thin-layer chromatographic separation of the dansyl-amino acids. The sequences of these tryptic peptides in conjunction with those of the chymotryptic peptides allowed the unequivocal deduction of portions of the sequence, but the final overlaps were provided by fragments obtained by specific chemical cleavage of the chain at aspartyl residues. The amino acid sequences deduced have documented the occurrence of a partial gene duplication in the gene product α2(F,S) of the Hp2(F,S) gene.
Omega-amino acids in rat brain
Authors: Yoshino Y. , DeFeudis F. V. , Elliott K. A. C.
Published: December 2009

Studies using paper and column chromatography indicate that rat brain contains 0.03–0.08 μmole of β-alanine per gram of tissue and less than 0.01 μmole/g of γ-amino-β-hydroxybutyric acid. After intravenous injection of U-14C-glucose no radioactivity appeared in these two substances.
Isolation of Neurospora crassa endonuclease specific for single-stranded DNA
Authors: Rabin E. Z. , Fraser M. J.
Published: December 2009

A method for the preparation from Neurospora crassa conidia of an endonuclease specific for single-stranded DNA is described. The enzyme was recovered from sonicates of conidia in high yield (51%) and was remarkably stable.
A kinetic study of the effects of δ-aminolevulinic acid upon the synthesis of embryonic and fetal hemoglobins in the blood islands of the developing chick blastodisc
Authors: Wainwright S. D. , Wainwright Lillian K.
Published: December 2009

Chick blastodiscs contained and synthesized a functional (embryonic) hemoglobin as early as the stage of the definitive primitive streak. The rate of hemoglobin synthesis in ovo rose dramatically at about the stage of the 3-somite embryo.Embryos explanted onto solid media at the 3-somite stage of development continued to synthesize hemoglobin in vitro for at least 12 h. The rate of synthesis rose markedly at the 6-somite stage of development, coincident with the onset of rapid synthesis of fetal hemoglobin. A supplement of exogenous aminolevulinic acid markedly stimulated the synthesis of hemoglobin before the 6-somite stage of development, but had little or no effect thereafter. These responses were obtained on both minimal and rich media. Levels of hemoglobin formed were characteristic of the final stages of development attained, regardless of initial stage of development, medium used, or time of incubation required to attain the final level of development.A new regulatory process resulting in elimination of a requirement for continuous presence of egg homogenate for maximal rates of hemoglobin was revealed. This took place between the 6- and 8-somite stages of development at the time of onset of rapid synthesis of fetal hemoglobin.
Inhibition of mitochondrial and bacterial protein synthesis by chloramphenicol
Authors: Freeman K. B.
Published: December 2009

The structural requirements for the inhibition of protein synthesis in mitochondria and in bacterial extracts by chloramphenicol isomers and analogues are similar. D-threo-Chloramphenicol and its p-methylthio, p-methylsulfonyl, and p-sulfamoyl analogues equally inhibit protein synthesis in isolated rat-liver mitochondria and extracts of Escherichia coli B. Fifty percent inhibition is at 15 μM and 10 μM, respectively. Analogues with larger p-substituents on the phenyl ring or with an m-chloro group are less inhibitory in both systems. L-threo-Chloramphenicol and deacylated chloramphenicol do not inhibit mitochondrial protein synthesis; with a dichloroacetyl group replacing the acetyl group on chloramphenicol 50% inhibition is at 65 μM, and L-erythro-chloramphenicol is 2% as inhibitory as D-threo-chloramphenicol. The inhibition of protein synthesis in intact E. coli B is in the order: chloramphenicol > p-methylthio > p-methylsulfonyl > p-sulfamoyl, 50% inhibition being at 4 μM for chloramphenicol.
Purification of Neurospora crassa endonuclease-resistant DNA–RNA hybrid
Authors: Fraser M. J. , Rabin E. Z. , Allen G.
Published: December 2009

Denatured calf thymus DNA has been transcribed in vitro with RNA polymerase of Micrococcus lysodeikticus. The DNA–RNA hybrid which formed in this system was found to be highly resistant to a purified Neurospora crassa endonuclease, while the unhybridized DNA and RNA were rapidly degraded. DNA–RNA hybrid with a purity of 62–75% was isolated in one step from the digest in 69–86% yield by chromatography on methylated albumin – kieselguhr. Further purification was obtained by density gradient centrifugation in Cs2SO4 solution. The purified hybrid had a buoyant density of 1.49 g cm−3 in Cs2SO4, intermediate between that of mouse tRNA marker (1.63 g cm−3) and calf thymus DNA (1.43 g cm−3). During sucrose density gradient centrifugation, the hybrid sedimented slightly faster than mouse tRNA marker. Evidence for the double-stranded nature of the hybrid was found by thermal denaturation of the complex. The RNA of the hybrid became increasingly sensitive to ribonuclease as the hybrid was heated at successively higher temperatures.
The metabolism of 17α-estradiol-3-glucoside and 17α-estradiol-3-glucuronoside in the rabbit
Authors: Williamson D. G. , Layne D. S.
Published: December 2009

The injection of 17α-estradiol-6,7-3H-3-glucuronoside-U-14C into a rabbit led to the excretion of 17α-estradiol-3-glucuronoside-17-N-acetylglucosaminide with a 3H/14C ratio twice that of the injected material. When 17α-estradiol-6,7-3H-3-glucoside-U-14C was injected, the same double conjugate was excreted, completely devoid of 14C. This indicates that 50% of the injected glucuronoside is excreted without hydrolysis of the glycosidic bond, while the glucoside is completely hydrolyzed in vivo and the steroid reconjugated with glucuronic acid.
Respiratory control, oxidative phosphorylation, respiration, rate of ATP hydrolysis, and ethylene evolution in subcellular particulate fractions from cotyledons of germinating seedlings
Authors: Stinson Robert A. , Spencer Mary
Published: December 2009

Respiration rates, with α-ketoglutarate or succinate as substrate, of mitochondria isolated from bean cotyledons at various stages during seedling germination were found to follow the rate of mitochondrial ATP hydrolysis. Respiration was maximum at 7 days after planting, and ATP hydrolysis was maximum at 5 days after planting. Cotyledon mitochondria exhibited respiratory control in the early stages of germination, but all control was lost by the 3rd day. ADP control of respiration was again established by day 6, was maximum at day 7, and had disappeared by day 10.Ethylene production from whole cotyledons at various stages during seedling germination followed ethylene production from a subcellular particulate fraction of these cotyledons. Certain parallels can be drawn between ethylene evolution, ATP hydrolysis, and respiratory control. The possible influence of each parameter on the others is discussed.
Studies of dialkyl ether phospholipids. I. Chemical synthesis of some model compounds
Authors: Chen Jung-Shou , Barton Peter G.
Published: December 2009

The syntheses of three 1,2-dialkyl-sn-glycero-3-phosphates and one new 1,2-dialkyl-sn-glycerol are described. 1,2-Dioctadecyl-sn-glycero-3-phosphate was obtained by phosphorylation of 1,2-dioctadecyl-sn-glycerol with diphenylphosphorodichloridate and subsequent catalytic hydrogenolysis. 1,2-Dioctadecyl-sn-glycero-3-(methyl)phosphorylcholine was prepared by phosphorylation of the same dialkyl glycerol with methylphosphorodichloridate and subsequent reaction with choline iodide. 1,2-Dimethyl-sn-glycerol was prepared by treatment of 3-benzyl-sn-glycerol with methyl iodide and KOH followed by hydrogenolysis to remove the protecting group. This compound was then phosphorylated with phenylphosphorodichloridate, the product allowed to react with choline iodide, and the iodide-free product hydrogenated catalytically to yield 1,2-dimethyl-sn-glycero-3-phosphorylcholine which was characterized as the cadmium chloride complex. Some improvements in an established synthesis of 1,2-dioctadecyl-sn-glycerol are described.
Multiple monoamine oxidases in rat liver mitochondria
Authors: Sierens L. , D'Iorio A.
Published: December 2009

Indirect evidence from the kinetics of oxidative deamination is presented for the existence of two different monoamine oxidases in rat liver mitochondria. The enzymes can be differentiated on the basis of their affinities for benzylamine and serotonin. Electrophoretic separation yielded two fractions, each with the characteristics predicted from the kinetic experiments.
Kinetic mechanism of phosphorylase a. I. Initial velocity studies
Authors: Engers H. D. , Shechosky S. , Madsen N. B.
Published: December 2009

Initial rate studies on rabbit muscle phosphorylase a were carried out in order to assign a kinetic mechanism to this enzyme, which plays an important role in the control of glycogen metabolism. Initial velocities were measured with varied concentrations of both substrates in each reaction direction, both in the presence and the absence of the modifier AMP. Data were analyzed with double-reciprocal plots and secondary replots of slopes and intercepts to yield kinetically derived dissociation constants which may be compared with dissociation constants determined by independent methods. Inhibition studies using UDP-glucose as a substrate analogue are also reported. Inhibition is competitive with glucose 1-phosphate and P1 and noncompetitive with glycogen.A suitable rate equation for this system has been derived, and it should apply to other two-substrate enzyme–modifier systems exhibiting similar kinetics. The results of this detailed kinetic analysis, in conjunction with the isotope exchange studies at equilibrium which are reported in the following paper, suggest the kinetic mechanism of phosphorylase a to be rapid equilibrium random Bi Bi, i.e. random addition of substrates to the enzyme, with ternary complex interconversion as the rate-limiting step in the reaction sequence.
Nonsteady-state analysis of multisubstrate enzymic reactions
Authors: Hurst R. O.
Published: December 2009

A method is outlined for deriving the full rate equation for an enzymic reaction by a chain differentiation procedure. The equation which is obtained by this method contains higher order derivatives of the velocity function. When these are equated to zero for the conditions descriptive of the steady state, the equation reverts to the usual form of the steady-state equation.
Studies on the effect of inflammation on rat serum proteins
Authors: Ashton F. E. , Jamieson J. C. , Friesen A. D.
Published: December 2009

The effect of turpentine-induced inflammation on rat serum proteins has been studied at short time periods of exposure to an inflammatory agent (5–96 h). There was an increase in protein-bound hexose and hexosamine of serum reaching a maximum at 48 h after administration of turpentine. Eight fractions were prepared from serum by a combination of chromatography on DEAE-cellulose and preparative electrophoresis on strips of gelatinized cellulose acetate. Most of the increase in protein-bound carbohydrate (77–86%) found in serum from experimental animals was located in three fractions following the fractionation procedure; immunological studies revealed the presence of fibrinogen and haptoglobin in two of these fractions. There was no evidence for the presence of a new protein in serum at short times of exposure to an inflammatory agent. Proteins present in the perchloric acid soluble and seromucoid fractions of serum were found in five fractions, only two of which contributed to the increase in protein-bound carbohydrate of serum found as a result of inflammation. Studies involving incorporation of labelled precursors of glycoprotein biosynthesis into fractions from serum indicated that the most likely explanation for the increase in protein-bound carbohydrate of serum, as a result of inflammation, was an increase in the rate of synthesis of certain serum glycoproteins.
Effects of puromycin aminonucleoside on protein synthesis in Absidia coerulea
Authors: Nicholls D. M. , Cohen J. H.
Published: December 2009

The incorporation of 14C-leucine, 14C-phenylalanine, and 14C-phenylalanyl-tRNA into protein was measured in ribosome preparations of the soil fungus Absidia coerulea. The incorporation depended on ribosomes and GTP, together with pH 5 fraction and an ATP-generating system, or cell sap. The addition of 5 × 10−5 M aminonucleoside to the fungal cultures in vivo decreased the subsequent incorporation in vitro except when the ribosomes were prepared with bentonite. The percentage dry weight and protein concentration in the 140 000 × g supernatant were decreased (15% and 30%, respectively) following addition of aminonucleoside in vivo. Preincubation of the cell-free system with 5 × 10−5 M or 5 × 10−4 M aminonucleoside caused a decrease in the. subsequent incorporation of 14C-leucine and 14C-phenylalanyl-tRNA into protein.
Rat epididymal adipose tissue acetyl-CoA carboxylase
Authors: Desjardins P. R. , Dakshinamurti K.
Published: December 2009

The properties of a partially purified acetyl-CoA carboxylase (acetyl-CoA:CO2 ligase (ADP), EC 6.4.1.2) from rat epididymal fat pads have been studied. The properties of the rat adipose tissue enzyme are similar to those of the liver in regard to the pH optimum and affinity for substrates and inhibitors. The rat adipose tissue carboxylase shows a pH-dependent, reversible cold inactivation.
Computer-based derivation of rate equations for enzyme-catalyzed reactions. II. Rate equations for isotopic exchange
Authors: Schulz Arthur R. , Fisher Donald D.
Published: December 2009

A computer-based method is employed for the reformulation of rate equations for enzyme-catalyzed reactions from the coefficient form to the kinetic form. This method is applied to equations for the initial rate of enzyme-catalyzed isotope exchange. In the reformulated equations, the coefficients of each rate equation term are expressed as maximum velocity of the initial rate of the net reaction, Michaelis constants, inhibition constants, and exchange constants. The definition of the exchange constant for a given reactant may be identical to one of the inhibition constants for that reactant.
Phosphonolipids. XXIII. Synthesis of phosphonic acid analogues of L-α-(N-methyl)cephalins
Authors: Baer Erich , Pavanaram Sripada K.
Published: December 2009

A procedure for the synthesis of the racemic as well as both enantiomeric forms of phosphonic acid analogues of α-(N-methyl)cephalins has been developed. The synthesis of two representative members of a homologous series of L-α-phosphono(N-methyl)cephalins with saturated aliphatic acid substituents is described in detail. They were obtained by phosphonylating D-α,β-distearin and D-α,β-dipalmitin, respectively, with (N-carbobenzoxy,N-methyl-2-aminoethyl)phosphonic acid monochloride and tri-ethylamine, and removing the protective carbobenzoxy group of the diaeyl-L-α-glyceryl-(N-carbobenzoxy,N-methyl-2-aminoethyl)phosphonates by catalytic hydrogenolysis. The (N-carbobenzoxy,N-methyl-2-aminoethyl)phosphonic acid and its monochloride were prepared by treating the sodium salt of (N-methyl-2-aminoethyl)phosphonic acid with carbobenzoxychloride, and converting the (N-carbobenzoxy,N-methyl-2-aminoethyl)phosphonic acid to the chloride by means of phosphorus pentachloride. α-Phosphono(N-methyl)cephalins, α-(N-methyl)cephalins, and α-cehalins with identical fatty acid substituents have similar melting points, specific rotations, and solubility properties. The α-phosphono(N-ethyl)cephalins can be readily separated from α-(N-methyl)cephalins and α-cephalins by thin-layer chromatography on silica gel H or G.
Defective respiration and oxidative phosphorylation in muscle mitochondria of hamsters in the late stages of hereditary muscular dystrophy
Authors: Jacobson B. E. , Blanchaer M. C. , Wrogemann K.
Published: December 2009

Skeletal muscle mitochondria were isolated from 33 dystrophic hamsters of the BIO 14.6 strain, aged 265 ± 13 (S.E.) days, by glass-on-glass homogenization in a sucrose–EDTA medium in the absence of the proteinase Nagarse. These organelles utilized O2 at half the normal rate with pyruvate/fumarate or palmitate as substrate in a manometric test system and exhibited decreased P/O ratios and phosphorylation rates with pyruvate/fumarate. In polarographic experiments the mitochondria from dystrophic muscle, supplemented with L-malate, had significantly depressed O2 uptake rates, respiratory control ratios, and phosphorylation rates with pyruvate, palmityl-L-carnitine, and acetyl-L-carnitine as substrates and low ADP/O ratios with pyruvate and palmityl-L-carnitine. Since the severity of the respiratory depression was similar with the three substrates, it appeared that the defect lay beyond acetyl-CoA in their common degradative pathway. Judging from the rapid rate of succinate and NADH oxidation, the respiratory chain was unimpaired. It was concluded that a defect was present in the tricarboxylic acid cycle of muscle mitochondria isolated without Nagarse from older dystrophic hamsters of the BIO 14.6 strain and that the defect was accompanied by a loose coupling of oxidative phosphorylation.
Partial purification of phosphodiesterase I from microsomes of rat intestinal mucosa
Authors: Hynie I. , Zbarsky S. H.
Published: December 2009

Intestinal mucosa was homogenized in Krebs–Ringer phosphate buffer, pH 7.4, containing 6% Dextran. After centrifugation, the sediment was rehomogenized in 0.24 M sucrose and the homogenate centrifuged. The supernatant material from both steps was combined and centrifuged at high speed through a layer of 25% sucrose to yield a pellet of microsomes. This pellet was suspended in Tris–HCl buffer, pH 8.4, made isotonic in KCl, and the suspension was sonicated and centrifuged. A suspension of the sediment in Tris–HCl buffer was shaken with t-amyl alcohol to yield the soluble enzyme in the aqueous phase. The enzyme was purified further by chromatography on DEAE-cellulose using elution with a KCl gradient in Tris–HCl buffer, pH 8, made 6 M in urea. Phosphodiesterase I and alkaline phosphomonoesterase were eluted in peaks which overlapped only partially enabling the collection of phosphodiesterase I free of Phosphomonoesterase. The enzyme solution was concentrated and freed of urea by pressure dialysis.
Biosynthesis of compounds similar to aspergillic acid
Authors: MacDonald J. C.
Published: December 2009

Aspergillus flavus PRL 932 grown on 2% yeast extract medium produced the following 1-hydroxy-2(1H)-pyrazinones (abbreviation, HPY): 3-isobutyl-6-isopropyl-HPY, 3,6-diisobutyl-HPY, 3-isobutyl-6-sec-butyl-HPY (aspergillic acid, the major product), and 3,6-di-sec-butyl-HPY.When the growth media consisted of 0.6% yeast extract plus 1% of certain amino acids, the structure of some of the HPYs produced suggested that the amino acid was a precursor in the biosynthesis. With a leucine supplement, the major product was 3,6-diisobutyl-HPY, and with an isoleucine supplement, the major product was 3,6-di-sec-butyl-HPY. With a valine supplement, the HPYs included 3,6-diisopropyl-HPY and 3-isobutyl-6-isopropyl-HPY. With a norvaline supplement, they included 3,6-dipropyl-HPY, 3-propyl-6-sec-butyl-HPY, and 3-isobutyl-6-propyl-HPY. From the structure of the HPYs, conclusions were drawn regarding the specificity of the biosynthesis.The HPYs were separated by reversed-phase partition chromatography and identified by their proton magnetic resonance spectra and mass spectra.
RNA distribution in Saprospira grandis: the absence of a highly 2′-O-methylated RNA species
Authors: Singh H. , Macey H. L. , Hillier B.
Published: December 2009

Analysis of the RNA content of Saprospira grandis and the rhapidosome particles isolated from this organism has not revealed the presence of an RNA species in which 70–85% of the ribose residues bear 2′-O-methyl substituents. Only about 1% of the total absorbance of cellular RNA appears as dinucleotide sequences containing a 2′-O-methyl-substituted ribose. Different subcellular RNA species are characterized by chemical analysis.
The activation of chymotrypsinogen by papain
Authors: Shaw M. C. , Kay T. , Viswanatha T.
Published: December 2009

Papain has been found to activate bovine chymotrypsinogen A. The optimal conditions for the activation are pH 5.0, temperature 23 °C, and enzyme/substrate ratio 1:20. The chymotrypsin obtained by the papain activation has been isolated. A significant difference between this enzyme and α-chymotrypsin is the absence of the three amino acids (Ser, Gly, and Leu) occupying the C-terminal of the A-chain of the former.
The regulation of protein synthesis in nephrotic rat liver ribosome preparations
Authors: Nicholls D. M. , Girgis G. R.
Published: December 2009

The incorporation of 14C-phenylalanine into peptide was measured in microsome and ribosome preparations of control and nephrotic rat liver homogenates. Microsomes and ribosomes were incubated with liver postmicrosomal supernatant (S105) and 14C-phenylalanine. Ribosomes were incubated with a control liver transferase preparation and 14C-phenylalanyl-tRNA. In the nephrotic preparations the incorporation of 14C-phenylalanine was greater than it was in the control preparations either with endogenous mRNA or poly U. Since ribonuclease activity did not differ in control and nephrotic preparations and since using bentonite to inhibit ribonuclease did not change the nephrotic effect, the increased incorporation could not be attributed to decreased ribonuclease activity.