bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of soluble mouse liver 21-desoxy-20α-hydroxysteroid: NADP 20α-oxidoreductase from 21-hydroxy-20α-hydroxysteroid: NADP 20α-oxidoreductase
Authors: Darrach Marvin , Krehbiel Ruth E. , Deeth Leslie A.
Published: December 2009

At least two 20α-faydroxysteroid dehydrogenases occur in the dialyzed high-speed supernatant fraction of mouse liver. These enzymes have been separated from each other with good yields of each and some of their kinetic properties have been studied. With corticosterone, 11-dehydrocorticosterone, and 11β-hydroxyprogesterone as substrates, it has been shown that the specificity of each enzyme is determined, in part, by the nature of the substituent at C-21, hence the enzymes have been designated 21-desoxy- or 21-hydroxy-20α-hydroxysteroid 20α-dehydrogenase. An enzymatic method is described for the preparation of 11β,20α-dihydroxy-4-pregnen-3-one.
In vitro biosynthesis of steroid sulfates by cell-free preparations from tissues of the laying hen
Authors: Raud H. R. , Hobkirk R.
Published: December 2009

The sulfurylation of estrone-6,7-3H, estradiol-17β-6,7-3H, and dehydroisoandrosterone-4-14C by laying hen liver, oviduct, and vaginal preparations was investigated. Purification and product identification included ether and ethyl acetate extraction, paper chromatography, and isotope dilution, before and after hydrolysis with a sulfatase preparation.The esterifying enzymes were found in the 105 000 × g supernatants of the three tissues. The liver preparation was many times more active in steroid sulfate synthesis than the corresponding oviduct or vaginal fractions. Sulfurylation of dehydroisoandrosterone displayed the same cofactor, pH, and temperature requirements as did that of estrone and estradiol-17β. The degree of dehydroisoandrosterone sulfate synthesis was considerably lower than that of the estrogens, however. It is suggested that the laying hen possesses an enzyme system which is more efficient for the sulfurylation of estrogens than of other steroids such as dehydroisoandrosterone.
The incorporation of cholesterol by Pythium sp. PRL 2142, and some of its effects on cell metabolism
Authors: Sietsma J. H. , Haskins R. H.
Published: December 2009

A method is described by which cell wall, protoplasmic membrane, and intracellular membrane fractions of Pythium sp. PRL 2142 were separated. Distribution of cholesterol among these fractions was determined. The major part of the cholesterol taken up by the cell was incorporated into the protoplasmic membrane, and the rest into the intracellular membranes. Other evidence, though indirect, that cholesterol is incorporated into the cell membranes includes: (a) the leakage of cell material from mycelium grown in the presence of cholesterol is much lower than that from mycelium grown without cholesterol; (b) four polyene antibiotics increase the leakage of cell material from mycelium grown in the presence of cholesterol but have no effect on mycelium grown in the absence of cholesterol. Some other effects of cholesterol on cell behavior are: (a) increase of the lactic acid and acetoin production and decrease of the oxygen consumption; (b) decrease of cellulase and laminaranase activity with a simultaneous effect on morphology; (c) increase of resistance against the antibiotic terrein.
Effects of radiation from 14CO2 absorbed by Pinus strobus L. seedlings during photosynthesis on their subsequent growth and metabolism
Authors: Ursino D. J. , Slankis V. , Krotkov G.
Published: December 2009

Several times during the year, white pine seedlings were placed in a closed system and each plant was permitted to photo-assimilate 400–500 μCi of 14CO2. At various periods of time after photo-assimilation, the fresh weight, apparent photosynthesis, dark respiration, and distribution of absorbed 14C throughout the seedlings were determined. The location and magnitude of depressed growth caused by the radiation from the incorporated 14C varied with the time of year when photo-assimilation occurred.When 14CO2 photo-assimilation occurred in May and June, suppression of growth was the greatest in the new shoots, whereas when photo-assimilation occurred in the fall, the suppression of growth was more pronounced in the roots. Seedlings which photo-assimilated 14CO2 in the fall appeared normal during winter but their buds failed to develop into new shoots the following spring.It is also suggested that a decrease in the rate of apparent photosynthesis may be used as an indicator of radiation damage brought about by the incorporated 14CO2.
Sources of sulfur in the thioglucosides of various higher plants
Authors: Wetter L. R. , Chisholm M. D.
Published: December 2009

L-Methionine-35S and DL-cysteine-35S were good sources of sulfur for the biosynthesis of sinigrin in Armoracia lapathifolia Gilib. and were incorporated with approximately the same efficiency. Homomethionine-35S was a slightly poorer source of sulfur than methionine, while taurine-35S was a very poor source. When homomethionine, methionine, and cysteine were employed as sources of sulfur, the distribution of radioactivity between the two sulfur atoms in sinigrin was approximately 80% in the isothiocyanate moiety and 10–15% in the sulfate moiety. When taurine was employed, the distribution was reversed. 1-Thio-β-D-glucose (1-thioglucose) also was a poor source of sulfur for sinigrin. The carbon skeleton of 1-thioglucose was only slightly incorporated into this thioglucoside. The experiments indicated that 1-thioglucose was not a direct precursor of the 1-thioglucosyl residue of sinigrin.The administration of doubly labeled methionine-2-14C-35S clearly demonstrated that this amino acid was not incorporated intact into sinigrin. The carbon-2 and sulfur atoms were metabolized by two different routes.Preliminary studies related to sulfur incorporation into the thioglucosides of Nasturtium officinale R.Br., Tropaeolum majus L., and Reseda luteola L. indicated that there were some differences depending on the source of sulfur; DL-cysteine was a better source of sulfur than either methionine or 1-thioglucose. Tropaeolum majus L. appeared to utilize the sulfur of cysteine for the production of thioglucoside as efficiently as Armoracia lapathifolia Gilib.; however, the other two species utilized the sulfur from the amino acids very poorly.
Conversion in vivo of injected estradiol-17β-4-14C and estrone-4-14C to urinary estradiol-17α-14C by the hen
Authors: Mulay Shree , Common R. H.
Published: December 2009

Radioactive estradiol-17α was identified in urine of hens that had received injections of estradiol-4-14C, or of estrone-4-14C, or of a mixture thereof. Identification was based on thin-layer chromatographic mobilities of the phenol and three derivatives, and by recrystallization of the phenol and of its diacetate in admixture with appropriate carrier to constant specific activity. The possibility of microbiological formation of the radioactive estradiol-17α after excretion of the urine was excluded by ad hoc experimentation. The results are advanced in support of the view that estradiol-17α is one of the normal urinary steroid estrogens of the fowl.
Absence of normal cell wall constituents from the outer layers of Halobacterium cutirubrum
Authors: Kushner D. J. , Onishi H.
Published: December 2009

Neither D-amino acids nor teichoic acid were detected in mechanically prepared envelopes of Halobacterium cutirubrum. If a rigid layer is responsible for the rod shape of these bacteria, its chemical nature remains unknown.
The inhibition of mammalian mitochondrial NADU oxidation by chloramphenicol and its isomers and analogues
Authors: Freeman K. B. , Haldar D.
Published: December 2009

Chloramphenicol and its isomers and analogues have been found to inhibit the oxidation of NADH, but not that of succinate, by beef heart mitochondria. They must therefore inhibit the NADH dehydrogenase segment of the respiratory chain. Chloramphenicol gave 50% inhibition at a concentration of 1 mM. The methylthio analogue of chloramphenicol inhibited NADH – coenzyme Q6 reductase but not NADH–ferricyanide reductase. Spectrophotometric observations suggest that these inhibitors act between NADH and flavin in coupled rat liver mitochondria and between flavin and cytochrome b in uncoupled beef heart mitochondria.
The inhibition of protein synthesis and respiration in mouse ascites tumor cells by chloramphenicol and its isomers and analogues
Authors: Haldar D. , Freeman K. B.
Published: December 2009

D(−)-threo-Chloramphenicol has been found to inhibit protein synthesis, respiration, and RNA synthesis in mouse ascites cells. These inhibitions are prevented by glucose. Chloramphenicol gives 50% inhibition of respiration and protein synthesis at between 1.4 and 1.6 mM and between 1.1 and 1.4 mM, respectively. In the presence of increasing amounts of chloramphenicol there is also a progressive drop in the level of ATP. Isomers and analogues of chloramphenicol inhibit both protein synthesis and respiration. The inhibitory strength decreases as follows: methylthio analogue, chloramphenicol, L(+)-threo-isomer, L-erythro-isomer, chloramphenicol base, methylsulfonyl analogue, and sulfamoyl analogue. The D(−)-threo- and L(+)-threo-isomers are taken up equally by the cells to a concentration of 1.1 to 1.4 times that of the medium. It is concluded that the inhibition of protein synthesis in ascites cells by chloramphenicol is not a direct effect but is due to the inhibition of respiration and ATP production, which in turn depends on the inhibition of NADH oxidation by the antibiotic. Rotenone has also been found to inhibit protein synthesis.
Nucleotide clusters in deoxyribonucleic acids. I. Isolation of purine oligonucleotides
Authors: Cape Ronald E. , Spencer John H.
Published: December 2009

The distribution of uninterrupted purine sequences in DNA has been studied by degradation of DNA with hydrazine and KOH, followed by DEAE-cellulose chromatography with a salt gradient. Conditions of hydrolysis previously reported have not yielded reproducible results. Reasons for this lack of reproducibility have been found to include excessively severe conditions of hydrazinolysis and the failure of alkaline hydrolysis to produce discrete oligonucleotides of a single type: Punpn+1. There is a steady release of inorganic phosphorus until stable oligonucleotides of general formula Punpn−1 are produced. The modified procedure described here has given reproducible results in our laboratory. An explanation of the mechanism of degradation of DNA by hydrazine and KOH is presented.
Studies on mouse liver 21-desoxy- and 21-hydroxy-20α-hydroxysteroid : NADP 20α-oxidoreductase
Authors: Krehbiel Ruth , Darrach Marvin
Published: December 2009

Corticosterone, 11-dehydrocorticosterone, 11β-hydroxyprogesterone, and 11-ketoprogesterone have been compared as substrates in the soluble mouse liver 21-hydroxy- and 21-desoxy-20α-hydroxysteroid : NADP 20α-oxidoreductase enzyme systems. Each enzyme showed a high specificity for catalyzing 20α reduction by NADPH2 that depended on the structure of the C-21 group. A much higher conversion rate was given by 11-dehydrocorticosterone than by corticosterone in the 21-hydroxy-20α-hydroxy-steroid 20α-dehydrogenase system whereas 11β-hydroxyprogesterone and 11-ketoprogesterone gave approximately the same rates in the 21-desoxy-20α-hydroxysteroid 20α-dehydrogenase system. Corticosterone and 11β-hydroxyprogesterone proved to be competitive inhibitors of the 20α reduction of 11-dehydrocorticosterone as substrate in the 21-hydroxy-20α-hydroxysteroid 20α-dehydrogenase system. Both corticosterone and substrate, but not 11β-hydroxyprogesterone, gave 20α-hydroxy derivatives. Similarly, 11-dehydrocorticosterone and 11-ketoprogesterone were competitive inhibitors of the 20α reduction of 11β-hydroxyprogesterone as substrate in the 21-desoxy-20α-hydroxysteroid 20α-dehydrogenase system. Both 11-ketoprogesterone and substrate, but not 11-dehydrocorticosterone, were converted to 20α-hydroxy derivatives. The new steroid 20α-hydroxy-4-pregnene-3,11-dione has been synthesized by chemical and enzymatic methods, and its properties and those of its acetate are recorded.
Some physical properties of the esterases of bovine liver
Authors: Ecobichon D. J.
Published: December 2009

The carboxylesterases of bovine liver were separated electrophoretically into a rapidly migrating band and a group of four slow bands of activity. Incubation of buffered samples at room temperature resulted in a loss of activity in the rapidly migrating band and a simultaneous rearrangement of the activity in the slower bands, with the formation of three new electrophoretic variants. By molecular-sieve studies in starch gel, by two-dimensional electrophoresis, and by gel filtration in Sephadex G-200, this heterogeneous group of esterases was found to be of similar molecular size though differing in net electrical charge.
Tritium–hydrogen exchange in insoluble collagen
Authors: Kingham D. J. , Brisbin D. A.
Published: December 2009

The rate and extent of exchange of collagen fibers with tritiated water has been investigated under various conditions, and four classes of hydrogen atoms are distinguishable. Of these classes, one exchanges too rapidly to be measured by this technique, a second exhibits rate curves similar to those observed in the absorption of water vapor, and a third class of hydrogen atoms shows a pH dependence remarkably similar to that expected for the titration curve of collagen. Lithium bromide treatment releases the fourth class for exchange as it severs the hydrogen bonds and destroys the structural features of the collagen macromolecule. Comparison of exchange under moderate chemical conditions with the total exchange suggests that two out of three peptide imino hydrogens may be hydrogen bonded in insoluble collagen, as is also suggested by one of the models proposed for the structure of the collagen macromolecule.
Changes in esterified fatty acids in the isolated, perfused rabbit heart
Authors: Kako K. , Dubuc M. J. G.
Published: December 2009

The hearts of fasted (48 h) or fed rabbits were perfused with buffer solution with or without glucose. The right ventricle was removed at the 10th min of perfusion. The left ventricle was perfused for 10, 70, or 130 min. Cardiac lipids were analyzed by the hydroxamic acid method and gas chromatography. The neutral lipid fraction from the heart of the fasted rabbit contained relatively more linoleic and less palmitic acid than that from the heart of the fed animal. Similarly, relatively more oleic and less stearic acids were found in the phospholipid fraction from the heart of the fasted rabbit. There was a slight difference in fatty acid distribution between the right and left ventricular lipids at the 10th min of perfusion.The left ventricle of the fasted rabbit lost two-thirds of its neutral lipid stores during perfusion for 120 min with a substrate-free medium. Some of the phospholipid also disappeared between the 70th and the 130th min of perfusion. No measurable loss of lipids was found in the hearts of fed animals perfused under the same conditions. In the presence of glucose in the perfusing medium, cardiac lipid contents remained unchanged during perfusion regardless of the nutritional state of the animal. Esterified fatty acid composition did not change significantly during perfusion. The significance of these observations is discussed in relation to possible metabolic control systems in fasted and fed animals.
Independence of growth hormone effects on nitrogen retention and free fatty acid mobilization
Authors: Cheng Jose S. , Kalant Norman
Published: December 2009

Bovine growth hormone (4 mg) was injected subcutaneously into two groups of rats, one group limited-fed and the other fed ad libitum. Four hours later, the respiratory quotient was found to be lowered and the plasma free fatty acid (FFA) level elevated. The oxidation rate of orally administered 14C-tripalmitin to 14CO2 and the oxygen consumption rate were not affected. Growth hormone administered for 9 days had a persistent suppressive effect on urinary nitrogen excretion and respiratory quotient in both groups but caused a maintained elevation of the plasma FFA level only in the ad libitum group. 14C-Tripalmitin oxidation and oxygen consumption rates were unaffected by growth hormone.
Some effects of phloridzin and quinacrine on photophosphorylation and carbon dioxide fixation by isolated spinach chloroplasts
Authors: Vose John R. , Spencer Mary
Published: December 2009

A 60–70% inhibition of spinach chloroplast PMS1-catalyzed cyclic photophosphorylation was observed following a 5-min pre-incubation in the dark with either 0.25 mM phloridzin or 10 μM quinacrine. Phloridzin was also shown to severely inhibit the endogenous synthesis of ATP (no catalyst being present). The inhibitors had only a slight effect on the fixation of carbon dioxide. Addition of 3-phosphoglyceric acid was found to inhibit the fixation of CO2 while ribose 5-phosphate stimulated CO2 fixation, even in the presence of 0.25 mM phloridzin.
In vitro O2′-methylation of sugars in E. coli RNA. II. Methylation of ribosomal and transfer RNA by homologous methylases in crude cell-free extracts and particulate suspensions from a relaxed mutant of E. coli
Authors: Nichols J. L. , Lane B. G.
Published: December 2009

(1) The ribosomal and transfer ribonucleates (rRNA and tRNA) from a relaxed strain of E. coli have been methylated in vivo, by growing the organism in a medium containing [methyl-14C]-methionine, and in vitro, by incubating cell-free preparations from both methionine-sufficient and methionine-deprived cultures with [methyl-14C]-S-adenosyl methionine.(2) Six base-methylated derivatives that were labeled in vivo were also found to be methylated in vitro. Three base-methylated components known to be present in E. coli RNA were not included in the present survey.(3) Seven sugar-methylated derivatives were labeled in vivo but only three of these were efficiently methylated, in vitro.(4) Ribose residues in "undermethylated" rRNA and tRNA can be O2′-methylated under the influence of homologous methylases when cell-free preparations are supplemented with S-adenosyl methionine.
The kinetic constants for the inhibition of acetylcholinesterase by phosdrin, Sumioxon, DDVP, and phosphamidon
Authors: Braid P. E. , Nix M.
Published: December 2009

The bimolecular rate constants for the inhibition of bovine erythrocyte Cholinesterase by dimethyl-2-methoxycarbonyl-1-methyl vinyl phosphate (phosdrin), dimethyl-3-methyl-4-nitrophenyl phosphate (Sumioxon), dimethyl-2,2-dichlorovinyl phosphate (DDVP), and dimethyl-2-chloro-2-diethylcarbamoyl-1-methyl vinyl phosphate (phosphamidon) are 1.36 × 105, 4.02 × 104, 1.56 × 104, and 6.30 × 102 1/mole per minute, respectively, at 37°. The inhibition reaction involves reversible complex formation followed by phosphorylation of the enzyme. The values of the complexing constant for phosdrin, Sumioxon, and phosphamidon are 6.90 ± 0.82 × 10−5, 1.38 ± 0.21 × 10−4, and 1.90 ± 0.50 × 10−2 M, respectively. The respective phosphorylation constants are 9.24, 5.58, and 9.36 min−1.
Studies on wheat plants using 14C-labelled compounds. XXII. Incorporation into wheat protein
Authors: McConnell W. B.
Published: December 2009

Thatcher wheat plants were labelled with 14C by injecting radioactive tracers into the top internode of the stem during late stages of plant growth. The distribution of 14C in fully mature plants was examined, emphasis being placed on the labelling of kernel-protein amino acids.Glutamine was only slightly more effective than glutamic acid for labelling glutamic acid isolated from the gluten hydrolysate, indicating that glutamic acid and glutamine are extensively interconverted in the wheat plants. Proline and glutamic acid also are readily interconverted, proline-14C yielding protein in which the glutamic acid has a higher specific activity than does the proline. By contrast, arginine-5-14C did not yield highly labelled glutamic acid.14C from glyoxylate-1-14C was widely distributed among kernel components but it produced glycine and serine with carboxyl carbons of exceptionally high specific activity.Succinate-1,4-14C, succinate-2,3-14C, and aspartic acid-14C all labelled glutamic acid of kernel protein more extensively than the other amino acids of the protein. The role of the tricarboxylic acid cycle in utilizing these tracers is discussed.
DNA synthesis in the developing rat brain
Authors: Sung Shan-Ching
Published: December 2009

The in vitro synthesis of DNA as measured by the incorporation of thymidine-2-14C into DNA has been studied for various regions of the infant rat brain. Both intact cerebellum and cell-free extracts of cerebellum from newborn and infant rat brain showed a very rapid rate of DNA synthesis which was highest around 6 days after birth and decreased rapidly thereafter up to 18 days. This DNA synthesis in developing rat brain was strongly inhibited by hydroxyurea but was much less sensitive than was RNA synthesis to inhibition by actinomycin D.
The biosynthesis of protamine in trout testis. I. Intracellular site of synthesis
Authors: Ling Victor , Trevithick John R. , Dixon Gordon H.
Published: December 2009

At a late stage of spermatogenesis, protamine, a sperm-specific protein of low molecular weight and high arginine content ([Formula: see text] of the total residues), appears in the nuclei of testis cells in salmonid and, related fish. This newly synthesized small protein progressively replaces the somatic histones in combination with DNA.Two column chromatography techniques (Bio-Gel P-10 and CM-cellulose) which are capable of completely separating protamine from histones and other testis basic proteins have been employed to identify and characterize newly synthesized protamine. When protamine synthesis begins, histone synthesis is decreased and eventually ceases. By pulse labelling testis cell suspensions for different lengths of time and analyzing the amount of 14C-protamme found in the cytoplasm and in the nucleus, the site of protamine synthesis can be shown to be in the cytoplasm. Further, a cell-free, isolated cytoplasmic fraction can incorporate 14C-arginine into whole protamine molecules, while both an isolated nuclear fraction and high-speed supernatant were relatively inactive. Sedimentation analysis of pulse-labelled testis ribosomes indicates that protamine is synthesized on a class of small polysomes, the disomes. Because of its highly basic nature, the release of protamine from the ribosomes and its subsequent transport into the nucleus, which appears to be rapid, may require special mechanisms.
The release of lipoproteins by rat liver slices
Authors: Kook A. I. , Rubinstein D.
Published: December 2009

The release of the lipid and protein moieties of lipoproteins by liver slices from rats charged in vivo with palmitate-9,10-3H and leucine-1-14C was followed. The replacement of Ringer solution as the incubation medium by serum resulted in an increase in the release of the labelled lipid moiety but had no effect on the radioactivity of the protein moiety. Analysis of the lipoproteins indicated that serum had no effect on the radioactivity of the neutral lipid in the lipoprotein of d < 1.063 or β-lipoproteins prepared by ultracentrifugation or heparin precipitation, respectively. However, the lipoprotein of d < 1.063 released into serum contained considerable amounts of labelled phospholipids and fatty acids which were not present in the β-lipoprotein precipitated by heparin or in the low density lipoproteins prepared by either procedure following incubation in Ringer solution. Following incubation of the slices in serum, but not in Ringer solution, the lipoprotein having d > 1.063 and the supernatant of the heparin precipitate contained considerable amounts of labelled phospholipid. It is concluded that serum may contain a lipoprotein capable of combining with liver phospholipids and that ultracentrifugation results in the separation of low density lipoproteins containing excess lipid.
Phospholipid metabolism in the molluscs. I. Distribution of phospholipids in the water snail Lymnaea stagnalis
Authors: Liang Chi-Rong , Strickland K. P.
Published: December 2009

The phospholipid distribution in the mollusc Lymnaea stagnalis was investigated by fractionation of the lipid extract with silica-gel column chromatography followed by qualitative and quantitative thin-layer chromatography. The results obtained show that choline and ethanolamine phosphoglycerides are the major phospholipids in this species and that they amount to about 50% and 30% of total phospholipids, respectively. The amount of ceramide 2-aminoethylphosphonate in this species is 7.5% of the total phospholipids and this compound is the main phosphonolipid in this species. The glyceryl ether derivatives of both choline and ethanolamine phosphoglycerides are found to be very high. Nearly half (45%) of the choline phosphoglycerides is glyceryl ether in nature while 15% of the ethanolamine phosphoglycerides is also of this type.
Purification of bacterial cholinesterase
Authors: Laing Allan C. , Miller Helen R. , Patterson Kathleen M.
Published: December 2009

The inducible cholinesterase of Pseudomonas fluorescens (Goldstein strain) was purified by fractionation on a CM-Sephadex column. The method was found to be superior to alumina C γ gel fractionation in terms of yield, specific activity of the enzyme, and reproducibility of results.
Phosphonolipids. XIX. Synthesis of a naturally occurring ceramide aminoethylphosphonate and its enantiomer
Authors: Baer Erich , Sarma G. Raghupati
Published: December 2009

The synthesis of erythro-N-palmitoyl-D-sphmgosyl-1-(2-aminoethyl)phosphonate and of its enantiomer is described. Comparison of the synthetic and natural ceramide aminoethylphosphonates revealed the latter to be derivatives of D-sphingosine.
Oxidative phosphorylation and adenosine triphosphatase activity in the liver mitochondria of rats administered with phenylhydrazine and hydroiyzed glucose cycloacetoacetate
Authors: Reddi T. G. , Nath M. C.
Published: December 2009

The effect of phenylhydrazine and hydroiyzed product of glucose cycloacetoacetate (GCAh) administration on the activity of adenosine triphosphatase (ATPase) in rat-liver mitochondria has been investigated. The results are discussed in relation to the efficiency of mitochondrial oxidative phosphorylation. Phenylhydrazine was found to increase the ATPase activity both in vitro and in vivo. However, preincubation or treatment with hydrolyzed glucose cycloacetoacetate resulted in an appreciable depression of this phenylhydrazine-enhanced enzyme activity. The liver mitochondria from phenylhydrazine-administered rats showed very little difference in milligrams of total protein, but the homogenates had a high protein content as compared to the preparations from normal rats and rats administered with hydrolyzed glucose cycloacetoacetate. With citrate as the substrate, normal rat-liver mitochondria exhibited a P/O ratio of 3.0. With the same substrate, the liver mitochondria from phenylhydrazine-administered rats lowered the oxygen uptake and ATP formation, thereby resulting in a decreased P/O ratio of 2.4, whereas administration of hydrolyzed glucose cycloacetoacetate prior to phenylhydrazine resulted in a partial restoration in oxygen uptake and ATP formation, and thus yielded a P/O ratio of 2.8.
Nucleotide clusters in deoxyribonucleic acids. II. Investigation of methods for isolation of pyrimidine oligonucleotides
Authors: Spencer John H. , Cape Ronald E. , Marks A. , Mushynski W. E.
Published: December 2009

Investigation of the degradation of DNA by H2SO4 under conditions designed to release pyrimidine 3′,5′ terminally phosphorylated oligonucleotides has revealed non-nucleotide products. Their presence detracts from the usefulness of this method for the quantitative analysis of the frequency distribution of pyrimidine oligonucleotides. An explanation of the mechanism of degradation of DNA by H2SO4 is presented. Such extraneous products are not present in formic acid – diphenylamine hydrolysates of DNA. A slight modification of the formic acid – diphenylamine method of hydrolysis, fractionation of the hydrolysate on a DEAE-cellulose column, and the use of a simple spectrophotometric method of analysis have made possible a rapid system of investigation of pyrimidine oligonucleotide clusters in DNA.
The enzymic deacylation of esterified mono- and di-saccharides. IV. The products of esterase-catalyzed deacetylations
Authors: Fink A. L. , Hay G. W.
Published: December 2009

Wheat germ lipase, or a purified esterase from it, catalyzed the deacylation of peracylated glucose and glucose-containing disaccharides in the pH range 5.6–8.1 at 25–37 °C with the substrate in either a homogeneous or heterogeneous state. Acetyl groups were hydrolyzed 12 times more rapidly than propionyl and 25 times more rapidly than benzoyl groups. Partially acylated compounds were separated by preparative chromatography. Analysis of these intermediates indicated a preferential order of removal of acetyl groups, namely [Formula: see text]. Measurement of initial rates of deacetylation were in accord with the results from the product analysis of the intermediates. The Km values for the peracetylated disaccharides were quite similar and exhibited an order of magnitude less than that observed for the monosaccharide.
Metabolism of phosphoglycerides in E. coli III. The presence of phospholipase A
Authors: Fung C. K. , Proulx P.
Published: December 2009

The breakdown of labelled phosphoglycerides by E. coli 015 and 0118 was studied in vitro. Phosphatidylcholine and phosphatidylethanolamine labelled in the 1-acyl ester position with 1-14C-stearic acid were hydrolyzed to 14C-label1ed fatty acid. 32P-labelled phosphatidylethanolamine yielded labelled lysophosphatidylethanolamine and water-soluble products. Deoxycholate favored the production of both 14C-labelled fatty acid and 32P-labelled lysophosphatidylethanolamine. It is suggested that part of the breakdown of phosphoglycerides is brought about by the action of phospholipase A1.
On the determination of the molecular weight of protein subunits on Sephadex G-200 in the presence of detergent. Glutamate dehydrogenase
Authors: Pagé M. , Godin C.
Published: December 2009

A standard curve was prepared by plotting the logarithm of the molecular weight of proteins against their elution volume on Sephadex G-200 in the presence of sodium dodecyl sulfate and p-hydroxymercuribenzoate, from which a linear relationship was obtained. Glutamate dehydrogenase was completely dissociated into its monomer subunits by incubation at room temperature in the column eluent for 24 h, and the elution volume of the monomer was determined. From this data, the monomer molecular weight of the subunit was found to be 47 500 ± 2500.
The utilization of 15N and phenylalanine-2-14C by wheat plants
Authors: Finlayson A. J. , McConnell W. B.
Published: December 2009

The distribution of 15N from ammonium chloride-15N in various parts of wheat plants following injection of the tracer into the stems at intervals during kernel formation has been examined. More specifically, the incorporation of the 15N and 14C from phenylalanine-2-14C into the "gluten" proteins and into the "salt-soluble" proteins has been studied. The results indicate that the location of 15N in the upper parts of the plant is markedly dependent upon the time of tracer injection and the data suggest that the gluten proteins and the salt-soluble proteins are formed independently of each other. The results also indicate that the rate of incorporation of phenylalanine into protein, relative to its metabolism by other pathways, increases as the plant matures.
Inhibition of glycolysis in Ehrlich ascites tumor cells incubated with formimino-L-glutamate
Authors: Fontenelle Lydia J. , Henderson J. Frank
Published: December 2009

Incubation of tumor cells with formiminoglutamate leads to inhibition of lactate synthesis from glucose, inhibition of phosphoribosyl pyrophosphate synthesis, and inhibition of purine ribonucleotide synthesis de novo and from purine bases. Lactate synthesis from inosine was increased. These effects may result from inhibition of triose phosphate isomerase by a metabolite of formiminoglutamate.
Coupling of p-nitropnenyl diazonium, fluoroborate to bovine chymotrypsinogen A and α-chymotrypsin
Authors: Maddaiah V. T.
Published: December 2009

p-Nitrophenyl diazonium fluoroborate couples at the ε-amino groups of lysyl residues of bovine chymotrypsinogen A and α-chymotrypsin in 0.5 M acetate buffer, pH 5.0. The reaction products are identified by spectral comparison with the model compound bis-(p-nitrophenylazo)-ε-amino-n-caproic acid. The reaction with the zymogen is about four times faster than with the active enzyme and this difference is independent of protein concentration. However, in the presence of 8 M urea, the reaction occurs at the histidyl groups at an equal rate. This suggests that of the groups that could undergo coupling, i.e. histidyl, tyrosyl, and lysyl, only the latter do so in the native proteins; moreover, chymotrypsinogen appears to have more such lysyl residues than does chymotrypsin.
Uridine phosphorylase and uridine kinase activities of the Ehrlich ascites carcinoma
Authors: Rainnie D. J. , Blair D. G. R.
Published: December 2009

Uridine phosphorylase and uridine kinase in cell-free extracts of the Ehrlich ascites carcinoma were assayed by a radioactive-tracer technique. Under the assay conditions uridine phosphorylase had an optimum pH of 8.0 and an apparent Km value for uridine of 2.5 × 10−3 M. Uridine kinase had a pH optimum of 6.6 and an apparent Michaelis constant for uridine of 2.4 × 10−3 M.The growth of the Ehrlich ascites carcinoma as indicated by the increase in the total packed cell volume was determined concurrently with the specific activities of uridine phosphorylase and uridine kinase, in order to ascertain the relationship of the specific activities of these enzymes to the progression of tumor growth. The specific activities of both enzymes varied during tumor growth, reaching maxima on the 11th day following the inoculation of 5.2 × 106 tumor cells into each mouse.
Effects of adenosine triphosphate and inorganic pyrophosphate on carbon dioxide fixation by isolated spinach chloroplasts
Authors: Vose John R. , Spencer Mary
Published: December 2009

The effects of exogenous ATP and inorganic pyrophosphate on CO2 fixation were investigated with preparations of intact spinach chloroplasts. Under illumination, both ATP and inorganic pyrophosphate resulted in an increase in the rate of CO2 fixation. These stimuli were generally equivalent to one another, and the degree of stimulation was dependent upon the age and condition of the chloroplasts used. During a reaction the enhancement effect increased with time; the initial kinetics (72 μmoles CO2 fixed per milligram chlorophyll per hour) were unaffected by either ATP or inorganic pyrophosphate. The stimulation of CO2 fixation by ATP or inorganic pyrophosphate was inhibited by a buffer pH of more than 8.0. Concentrations of exogenous magnesium above 0.25 mM were found to inhibit both the ATP- and inorganic pyrophosphate-induced increases in CO2 fixation. Phloridzin was found to partially inhibit the enhancement of CO2 fixation by ATP and inorganic pyrophosphate.
The purification of transketolase from Candida utilis
Authors: Kiely M. E. , Tan E. L. , Wood T.
Published: December 2009

Transketolase (EC 2.2.1.1) was purified 12-fold from an extract of dried Candida utilis by two fractionations with acetone followed by chromatography on DEAE-Sephadex. The fractions from the column were free from D-ribose 5-phosphate ketol isomerase and D-ribulose 5-phosphate 3-epimerase and could be used for the assay of D-xylulose 5-phosphate and of the epimerase. Three peaks of transketolase activity were eluted from the chromatography column; the material from each peak had a Michaelis constant for D-xylulose 5-phosphate close to the mean value for the three peaks of 6.8 × 10−5 M and gave the same two-banded pattern on cellulose acetate electrophoresis. When transaldolase was present in the material placed on the column, it appeared with transketolase in each of the three peaks. The enzyme could be stored for several months, in solution frozen at −20°. Dialysis against water caused a loss of activity which could be restored by the addition of thiamine pyrophosphate. The enzyme catalyzed the condensation of hydroxypyruvate with D-glyceraldehyde phosphate to form D-xylulose 5-phosphate.
In vitro screen of inhibitors of rat brain serotonin synthesis
Authors: McGeer E. G. , Peters D. A. V.
Published: December 2009

Over 700 compounds were screened at 10−4 M concentration as inhibitors of the conversion of L-tryptophan-14C to serotonin-14C in crude rat brain homogenates. Most of the compounds had little or no inhibitory effect. Those with strong inhibitory properties were tested as inhibitors of 5-hydroxytryptophan decarboxylase and, if active on the decarboxylase, were assayed as tryptophan hydroxylase inhibitors. Except for a few oxidizing and complexing agents and for some substituted p-phenylenediamines, the compounds found to inhibit tryptophan hydroxylase by >50% belonged to the three types of inhibitors already known, i.e. catechols, phenylalanine and ring-substituted phenylalanines, and 6-substituted tryptophans. The numerous data in this screen make possible some comments as to the structural requirements for activity within each class. A comparison of the results on tryptophan hydroxylase with data on tyrosine hydroxylase inhibition in similar homogenates makes it clear that two separate, if somewhat similar, enzymes are involved.
Benzoyl esterases of fungi
Authors: Reese E. T. , Maguire Anne , Parrish F. W.
Published: December 2009

Esterases produced by eight species of fungi are capable of hydrolyzing the benzoyl esters of simple sugars. These benzoyl esterases are of two types based on their specificities. One type acts on a broad band of benzoyl esters, including benzoylcholine, and is found only in Aspergillus terricola. The other type is strongly influenced by the position of the benzoyl group on glucose, and by the sugar on which it occurs. It is represented here by seven species of fungi. Both types are strongly inhibited by Phosdrin, and are unaffected by sodium fluoride.
Estrogen conjugates of hen's urine
Authors: Mathur Rajesh S.
Published: December 2009

Estrone-6,7-3H and ornithine-5-14C were injected concurrently into a hen and the steroid-conjugated fractions of the urine subsequently excreted were examined for the presence of radioactive phenolic steroids. The results indicated that neither estrone-6,7-3H nor its phenolic in vivo conversion products were excreted as conjugates with ornithine. Possible biliary excretion of such conjugate(s), however, was not excluded by the experiment.
Manganese in the fresh water clam
Authors: Seah T. C. M. , Hobden D. J.
Published: December 2009

Almost all the metabolically inactive manganese in the gill tissue of the fresh water bivalve mollusc Elliptio complanatus (Solander) can be extracted with a 10% neutral solution of EDTA (ethylenediamine-tetraacetic acid). The extracted manganese is in the trivalent state. Inorganic pyrophosphate is also found in the extract. A complex of manganipyrophosphate could account for the observed properties of the metal in vivo.
S-Adenosylethionine as an inhibitor of tRNA methylation
Authors: Moore B. G. , Smith R. C.
Published: December 2009

S-Adenosylethionine was shown to inhibit the methylation of tRNA by S-adenosylmethionine. Lineweaver–Burk plots of kinetic data suggested that the inhibition was competitive. Another known inhibitor of tRNA methylation, adenine, also exhibited competitive inhibition kinetics. A derivative of S-adenosylethionine, ethylthioadenosine, also inhibited the reaction and displayed a competitive inhibition pattern. These data were obtained using Escherichia coli K12W6 as a source of methyl-deficient tRNA and methylase enzymes. Preliminary data indicate that S-adenosylethionine is even a better inhibitor of rat methylases.Methylase activity of ethionine-fed rats was elevated, which suggested that the inhibition reaction with S-adenosylethionine and the increased methylase activity may proceed by two different pathways.
Ultraviolet circular dichroism measurements on wheat embryo ribosomes and their constituent ribonucleates and proteins
Authors: Wolfe Fred H. , Kay Cyril M.
Published: December 2009

Circular dichroism measurements on wheat embryo ribosomes and their constituent RNA and proteins under conditions of physiological environment support the conclusion drawn from optical rotatory dispersion studies that the base-paired conformation of RNA in the ribosome is similar to that in the free state. Measurements on these systems in the virtual absence of salt suggest that the RNA in the ribosome maintains its double-helical character largely through stabilization interactions with the structural ribosomal proteins. In addition, no conformational change accompanies the dissociation of the 80 S ribosomal particle into its 40 and 26 S subunits.
Phosphonolipids. XX. Total synthesis of a naturally occurring ceramide aminoethylphosphonate and of its enantiomer
Authors: Baer Erich , Sarma G. Raghltpati
Published: December 2009

The first synthesis of a naturally occurring C18-ceramide aminoethylphosphonate is described. The erythro-N-palmitoyl-D-sphingosyl-1-(2-aminoethyl)phosphonate was obtained by phosphonylation of erythro-N-palmitoyl-3-0-benzoyl-D-sphingosine with (2-phthalimidoethyl)phosphonic acid chloride and triethylamine, and consecutive removal of the protective phthaloyl and benzoyl groups of the reaction product, erythro-N-palmitoyl-3-0-benzoyl-D-sphingosyl-1-(2-phthalimidoethyl)phosphonate, by hydrazinolysis and mild alkaline hydrolysis, respectively. The unnatural l isomer was prepared in an analogous manner from erythro-N-palmitoyl-3-0-benzoyl-L-sphingosine. Comparison of the synthetic and natural ceramide aminoethylphosphonates confirmed the structure tentatively assigned by Rouser, Hori, and Hayashi and their colleagues to the C18-ceramide aminoethylphosphonates of a variety of shellfish, snails, and cephalopods, and established the fact that the natural ceramide aminoethylphosphonates are derivatives of D-sphingosine.
Cholesterol metabolism and vitamin B6. I. Hepatic cholesterogenesis and pyridoxine deficiency
Authors: Lupien P. J. , Hinse C. M. , Avery M.
Published: December 2009

Hepatic cholesterogenesis was studied in pair-fed and pyridoxine-deficient rats as well as in rat liver homogenate systems. Crossover of various subcellular components from pair-fed homogenates into pyridoxine-deficient homogenate systems and vice versa was also done.On 8 weeks of pyridoxine deficiency, acetate-14C incorporation rates into liver cholesterol increased by a factor of approximately 10. The same phenomenon was observed with the total liver homogenate systems.Pyridoxine deficiency does not appear to affect HMG-CoA reductase activity of pyridoxine-deficient liver microsomes sufficiently to explain the rapid acetate-1-14C incorporation rates in this same tissue. The activating system(s) responsible for the 10-fold increase in acetate-14C incorporation rates into pyridoxine-deficient rat liver cholesterol appears to be located in the high-speed supernatant fraction. Other subcellular components such as lysosomes and mitochondria are probably implicated to some extent in this phenomenon. The results indicate that vitamin B6 is necessary for normal hepatic cholesterogenesis in the rat.The significance of these findings and the possible relationship between these factors are discussed.
A matrix transformation method for writing the rate equations for complementary enzymic reactions
Authors: Hurst R. O.
Published: December 2009

A procedure is outlined for writing two rate equations that will yield the same product-inhibition pattern for an enzymic reaction. The definitions of the kinetic constants and the structure of the distribution equations for the enzyme intermediates as well as the order of interaction of the enzyme with the reactants will be different. A list of several mechanisms which can be qualified in this way is included.
Mammalian dihydroorotate – ubiquinone reductase complex. II. Correlation with cytochrome oxidase, mode of linkage with the cytochrome chain, and general properties
Authors: Miller Richard W. , Curry Jack R.
Published: December 2009

Evidence is presented showing that a dihydroorotate-oxidizing system sediments with mitochondrial enzymes of beef liver in a sucrose gradient. Spectrophotometric experiments now indicate that dihydroorotate is as effective as succinate in reducing the cytochrome b content of whole and sonically disrupted mitochondria. The pyrimidine precursor also reduces the entire cytochrome chain under anaerobic conditions. Additional characterization of the dihydroorotate – ubiquinone reductase complex was carried out with regard to pH and temperature stability, and optima, metal inhibition, and behavior in gel filtration chromatography.
The effects of dietary fat on fatty acid synthesis and malic enzyme activity in liver from growing chicks
Authors: Goodridge Alan G.
Published: December 2009

Hepatic malic enzyme activity and incorporation of glucose-U-14C into fatty acids in liver slices was no greater in birds fed fat-free diets than in those fed the same diets supplemented with corn oil. The results suggest that in the chick, in contrast to the rat, dietary fat does not suppress hepatic lipogenesis.
Rapid quantitative separation of long-chain fatty acids from neutral lipids
Authors: Durocher Jean-Guy , Leboeuf Bernard
Published: December 2009

On a microcolumn of neutral alumina, long-chain fatty acids are quantitatively retained. Neutral lipids including cholesteryl esters, triglycerides, diglycerides, and fatty acid methyl esters, as well as cholesterol, are quantitatively recovered in the effluent without hydrolysis of ester groups. Monoglyceride recovery is, however, only 96 ± 2%. Preparation of the column and chromatography may be accomplished in less than 45 min.
The nitration of cytochrome c
Authors: Skov K. , Hofmann T. , Williams G. R.
Published: December 2009

When cytochrome c is treated with tetranitromethane, two tyrosines (positions 48 and 67) are nitrated. The effects of this modification are described.
Metabolism of 75Se-selenite by human whole blood in vitro
Authors: Lee Melvin , Dong Alice , Yano Joyce
Published: December 2009

When 75Se, as selenite, is added to human blood it is rapidly taken up by the cells (50–70% within 1–2 min) and is then released into the plasma so that most of the radioactivity is in the plasma by 15–20 min. Uptake is inhibited by 10−3 M cyanide. The release of radioactivity from the cells is inhibited by 10−3 M para-chloromercuribenzoate and by 10−3 M iodoacetamide, although these agents do not affect uptake. Azide and 2,4-dinitrophenol (at 10−3 M) do not affect either process. Large quantities of sulfite, sulfate, and selenate (1000 times as much S or Se as 75Se) do not affect uptake or release, but large amounts of selenite (1000 times) inhibit release. The release rate follows first-order kinetics and increases with temperature. 75Se released from cells is bound by a plasma protein but can be removed from the protein by treatment with cysteine. Studies suggest that the released selenium is in an altered form or state, although this product has not been characterized. A hypothetical pathway for the metabolism of selenium is presented to account for the observations.
Disc electrophoresis of snake venoms. I. A qualitative comparison of the protein patterns from the species of Crotalidae and Elapidae
Authors: Basu Arun S. , Parker Reno , O'Connor Rod
Published: December 2009

The electrophoretic patterns of venom proteins of different species of snakes from the families of Crotalidae and Elapidae were studied by disc electrophoresis using different concentrations of polyacrylamide gel and different pH conditions. A qualitative comparison of the electropherograms showed variations in the distribution of proteins among different species and subspecies of snakes. It is suggested that the classification of venomous snakes from the standpoint of venom compositions is of fundamental importance in snakebite pathology.