bluuebunny/crossref_metadata_2025 huggingface dataset:
The Histidine and Methionine Sequences of Rabbit Skeletal Tropomyosin
Authors: Hodges R. S. , Smillie L. B.
Published: December 2009

Amino acid analyses of tropomyosin have previously shown four histidine and 13–14 methionine residues per mole (70 000 daltons) of tropomyosin. The isolation of two unique histidyl and five unique methionyl sequences is described. The number of unique methionyl peptides will undoubtedly be increased when more extensive sequence information becomes available although the value of 2 for the unique histidine sequences is considered to be a maximal one. These data support the conclusion that the two subunits of tropomyosin are similar in amino acid sequence. Both the acetylated NH2-terminal and COOH-terminal sequences of the protein have been determined in this study. The isolation and sequence analysis of two varieties of peptides arising from the COOH-terminus of the protein indicates either a degree of proteolysis during its isolation or a difference in the constituent polypeptide chains of tropomyosin in this region of their structures. The limited sequences reported indicate a repeat of hydrophobic residues as required by the inter-chain packing of a coiled-coil structure.
Cysteine Sequences of Rabbit Skeletal Tropomyosin
Authors: Hodges R. S. , Smillie L. B.
Published: December 2009

Amino acid analyses of tropomyosin have shown three cysteine residues per mole (M.W. 70 000) of tropomyosin. The cysteine content was determined by cysteic acid determinations, incorporation of 14C-labelled iodoacetic acid into the protein, and the analysis of S-carboxymethylcysteine after acid hydrolysis. The isolation of three unique cysteinyl peptides is incompatible with a homogeneous tropomyosin preparation of two chemically identical subunits. The amino acid sequences reported in this study indicate a regular repeat of hydrophobic residues as required by the inter-chain packing of a coiled-coil structure.
Further Codon Assignments in an Extremely Halophilic Bacterium using a Cell-Free Protein-Synthesizing System and a Ribosomal Binding Assay
Authors: White B. N. , Bayley S. T.
Published: December 2009

Further codon assignments were made in a cell-free protein-synthesizing system from Halobacterium cutirubrum by use of the random copolyribonucleotides, poly CU, poly CI, poly CG, and poly AU. Polymers containing significant amounts of adenosine precipitated in the high salt concentration of the system and this prevented examination of many of the codons by this technique. An assay for codon recognition and interaction of aminoacyl-tRNA with ribosomes was developed in order to utilize oligoribonucleotides which had a high proportion of adenosine but which would not precipitate in the high salt systems. The codon AAA was assigned to lysine on the basis of this technique. It was found that glutaminyl-tRNAGln was made via the intermediate glutamyl-tRNAGln as it is in Gram-positive bacteria.
Mammary Gland Nuclear RNA Polymerase Activities in Pregnant, Lactating, and 7,12-Dimethylbenz(α)anthracene-Induced Mammary Tumor-Bearing Rats
Authors: Mendelson I. S. , Anderson K. M.
Published: December 2009

RNA synthesis catalyzed by nuclei isolated from mammary glands of pregnant and lactating rats and from 7,12-dimethylbenz(α)anthracene-induced mammary tumors was examined, and the following observations were made.(1) Assay 1 (6 mM Mg2+, low ionic strength, nucleolar polymerase I), and assay 3 (2 mM Mg2+, 1.6 mM Mn2+, 0.3 M ammonium sulfate, high ionic strength, nucleoplasmic polymerase II) promoted synthesis of ribosomal-like (rRNA) and nonribosomal-like RNA (dRNA), respectively, as verified by differential sensitivity to actinomycin D, double-labelling experiments, and response to α-amanitin.(2) Synthesis of a rRNA-like product was increased in assay 2 (6 mM Mg2+, 0.02 M ammonium sulfate), compared with assay 1; in assay 3 increased formation of a more dRNA-like product occurred. Stimulation of mammary gland nuclear RNA synthesis by ammonium sulfate is biphasic, similar to the response of rat liver and sea urchin nuclei.(3) In assay 1, more rRNA was synthesized at 30° than at 37°; in assay 3 somewhat greater synthesis of dRNA occurred at 37° compared with 30°. The pH optima in assays 1 and 3 of 8.0 and 8.5, respectively, are the opposite of those reported for rat liver nuclei.(4) During pregnancy, isolated nuclei synthesized more dRNA-like product, compared to lactation; nuclei from lactating glands formed more rRNA, than during pregnancy. Nuclei from slowly growing tumors (Ts) examined in the three assays were 30–50% as active, while those from rapidly growing tumors (Tf) exceeded the activities of nuclei from pregnant (P) or lactating (L) rats.(5) P, L, and Ts nuclei incubated in assay 3 with α-amanitin were inhibited about 60%, compared to an 80% reduction with nuclei from tumors that were growing rapidly. The ratio of the base G to either A or U did not return to that of assay 1 or 2 (rRNA). This result is consistent with the presence of a third nucleoplasmic RNA polymerase (enzyme "III"), as described with rat liver and sea urchin nuclei.(6) Nuclei from proliferating normal and neoplastic tissues exhibited greater polymerase II activity, and the ratio of nucleoplasmic to nucleolar enzyme activity was increased. Changes in activities of enzyme II and enzyme "III" do not appear to be necessarily coordinate.(7) The pattern of polymerase activity in P and L nuclei is probably related to cellular proliferation and/or hypertrophy during pregnancy, and cellular function represented by milk protein synthesis with lactation. RNA polymerase activity in T nuclei correlated with the growth rate of the parent tumor and not with its histology, at least not in any simple way.
Experimental Allergic Encephalomyelitis (E.A.E.): Synthesis of the 7–11, 11–20, and 12–20 Peptides of Human Encephalitogenic Protein and Inhibition of Histological E.A.E. by the 12–20 Peptide
Authors: Barton M. A. , McPherson T. A. , Lemieux R. U. , Bain G. O.
Published: December 2009

Peptides comprising the 7–11, 11–20, and 12–20 sequences of human encephalitogenic basic protein (HEP) were synthesized by the solid-phase procedure, purified by gel-filtration and high-voltage paper electrophoresis, and characterized by amino acid analysis, thin-layer chromatography, high-voltage paper electrophoresis, and paper chromatography.The peptides were studied for the capacity to induce E.A.E. when injected with Freund's complete adjuvant (FCA) into guinea pigs. The same peptides were also studied for the capacity to inhibit development of E.A.E. in guinea pigs injected with peptide/FCA 28 days before injection with encephalitogenic HEP in FCA. The results were as follows: (1) all three peptides induced mild clinical E.A.E. but the 12–20 peptide induced severe disease in five out of 40 guinea pigs; (2) none induced histological lesions typical of E.A.E.; (3) none induced antibody reactive with 125I-HEP; (4) none induced delayed sensitivity to the homologous peptide or HEP; (5) injection of the 12–20 peptide in FCA inhibited the development of histological E.A.E. in guinea pigs injected later with HEP/FCA, whereas the 7–11 and 11–20 sequences did not; (6) humoral immunity to injection of HEP/FCA was not prevented by prior injection of the synthetic peptides in FCA.
The Separation of two Deoxyribonucleases from Extracts of Intestinal Mucosa of the Rat
Authors: Lee C. Y. , Lawrence Sheilia , Zbarsky S. H.
Published: December 2009

Two deoxyribonucleases have been demonstrated in cell-free extracts of rat intestinal mucosa. The enzymes were separated by ion-exchange chromatography on DEAE-cellulose and further purified by partition on hydroxyapatite. One DNase had optimum activity at pH 6.8–7.0 in ammonium acetate buffer, required Mn2+ or Mg2+ for activity, and was inhibited by EDTA. This enzyme is a DNase I by Laskowski's criteria Advan. Enzymol. 29, 165 (1967). The second enzyme was a DNase II with optimum activity at pH 3.5–4.0 in sodium formate buffer, was not inhibited by EDTA, and showed no requirement for divalent cations. Both enzymes were active only with native DNA and had no action on heated DNA or purified yeast transfer RNA.
Nucleoside Transport in Human Erythrocytes: Equilibrium Exchange Diffusion of Uridine
Authors: Pickard M. A. , Paterson A. R. P.
Published: December 2009

A rapid, saturable exchange between internal and external uridine takes place in suspensions of human erythrocytes under equilibrium conditions which preclude net transport of uridine. Maximum rates for this process are several times higher than those for net inward flux of uridine.
17α-Hydroperoxypregnenes. IV. A Comparative Study of their Fragmentation by Electron Impact and High Temperature Chromatography
Authors: Tan L. , Wang H. M. , Falardeau P.
Published: December 2009

The fragmentation of 17α-hydroperoxypregnenolone and 17α-hydroperoxyprogesterone by electron impact and thermolysis is described. It is shown that the fragmentation pattern follows a common pathway for both compounds, determined exclusively by the substituents at ring-D. A new reaction in steroid chemistry, termed deoxygenation, is discovered and its mechanism explained by intramolecular hydrogen abstraction via a six-membered cyclic transition state involving the 20-ketone group.
Regulation by Phosphoenolpyruvate of Fructose-1,6-diphosphatase in Skeletal Muscle: Evidence for an Allosteric Activator of the Enzyme
Authors: Behrisch Hans W.
Published: December 2009

Fructose-1,6-diphosphatase (FDPase) from muscle of three cold-water crustaceans was found to be activated by phosphoenolpyruvate (PEP). PEP appears to reduce Km for FDP at low and high temperatures; however, at low temperature the effect on Km of FDP is amplified. In addition PEP reduces affinity of FDPase for AMP, the allosteric inhibitor of the enzyme. These results suggest a coupling of several of the regulatory steps in the glycolytic and gluconeogenic sequences. In addition, skeletal muscle of the crustaceans used in the present study contains substantial (higher than 500 μmol/h/g tissue) activities of the gluconeogenic enzymes phosphoenolpyruvate carboxykinase, pyruvate carboxylase, and glucose-6-phosphatase. On the basis of these results it is proposed that gluconeogenesis is a functioning pathway in crustacean muscle.
Extractability of Histones from Formalin-Treated Nuclei of L-Cells
Authors: Yoo B. Y. , Krause M. O.
Published: December 2009

Treatment of isolated L-cell nuclei with cold buffered formalin for 40 min was found to decrease the extractability of histones with trypsin and with 0.25 N HCl. Among the various fractions separated on P-60 exclusion chromatography or by acrylamide gel electrophoresis, F1 was found to be preferentially extracted with HCl after formalin treatment, while F2a1 was found to be relatively more resistant to HCl or trypsin extraction in both formalin-treated and control nuclei. In the latter case, however, formalin treatment resulted in a drastic reduction in the effectiveness of trypsin digestion. After treatment for 30 min with trypsin (0.1 mg/ml) in Tris buffer, pH 7.0, only 29% of F2a1 was removed as compared with 85–95% of the other histone fractions. These results are discussed in the context of a possibly more protected localization of histone F2a1 in the chromatin.
Possible Interrelationship of Ethanol Metabolism and Choline Oxidation in the Liver
Authors: Tuma D. J. , Barak A. J. , Schafer D. F. , Sorrell M. F.
Published: December 2009

Since it has been demonstrated that ethanol increases choline uptake in liver, this study was designed to determine whether this is a direct effect of ethanol or a result of ethanol metabolism. This study also sought to determine whether oxidative degradation of choline regulates choline uptake in the liver and if ethanol-induced choline uptake is effected through the action of choline oxidase.Using the isolated perfused-liver technique to study choline uptake, it was found that the addition of pyrazole, an alcohol dehydrogenase inhibitor, to the perfusate completely inhibited the effect of ethanol on choline uptake. This work suggested that ethanol metabolism is necessary to obtain the ethanol effect. Experiments with guinea pig livers, which contain very little choline oxidase, and the use of a choline oxidase inhibitor in rat experiments showed that choline uptake is partially regulated by choline oxidase. The choline oxidase inhibitor was also shown to inhibit the ethanol effect on choline uptake, suggesting that increased choline requirement due to alcohol ingestion may be the result of ethanol metabolism stimulating oxidative degradation of choline.
Repair Synthesis of DNA in HeLa and L-celis Following Treatment with Methylnitrosourea or Ultraviolet Light
Authors: Walker I. G. , Ewart D. F.
Published: December 2009

Repair synthesis of DNA was measured in HeLa and L-cells following treatment with either ultraviolet (U.V.) light or methylnitrosourea (MNUA). HeLa cells exhibited 10 and 30 times more repair synthesis after U.V. light and MNUA treatment, respectively. HeLa cells were considerably more sensitive than L-cells to U.V. light and MNUA. MNUA formed the same kinds and amount of methylation products in the DNA of both cell lines. During post-treatment incubation, the overall rate of loss of these products from the DNA was similar in both cell lines. The minor product 3-methyladenine was preferentially removed from the DNA of HeLa cells but not L-cells. When previous studies with Chinese hamster and normal human fibroblasts were considered along with the present results it appeared that rodent cells not only exhibited less repair synthesis than human cells, but they were less sensitive to methylating agents and ultraviolet light.
Ouabain-Induced Seizures in Rats; Relationship to Brain Monoamines
Authors: Izumi K. , Donaldson J. , Minnich J. , Barbeau A.
Published: December 2009

Ouabain (5 μg) was injected into the left lateral ventricle of unanesthetized rats. Running seizures were observed in 81%, leaping seizures in 44%, and whole body flexion seizures in 31% of the animals after 5 μg of ouabain. At lower doses (0.5–2.0 μg) of ouabain, hypersensitivity to sensory stimuli was observed without seizure activity. With higher doses (10–500 μg) of ouabain, increasing severity of seizure pattern was seen. Monoamine estimations made on brain regions from animals sacrificed 15 min after injection of 5 μg of ouabain showed significant increases of serotonin in the hippocampus and decreases of norepinephrine in the midbrain region.
Biochemistry of Polyglycerophosphatides. The Mechanism of Cardiolipin Biosynthesis in Isolated Mitochondria
Authors: Stanacev N. Z. , Davidson J. B. , Stuhne-Sekalec L. , Domazet Z.
Published: December 2009

The mechanism of cardiolipin biosynthesis in isolated rat liver mitochondria was studied using endogenously formed and exogenously supplied phosphatidylglycerol-2′-3H in the presence and absence of added Mg2+, Mn2+, CDP-DL-dioleate, and CDP-D-diglyceride-2-14C. With endogenously formed and membrane-bound phosphatidylglycerol-2′-3H and in the presence of Mn2+, the incorporation of CDP-D-diglyceride-2-14C into cardiolipin-3H,14C was demonstrated, establishing the participation of both phosphatidylglycerol-2′-3H and CDP-D-diglyceride-2-14C in the formation of cardiolipin-3H,14C. In addition, the release of water-soluble labeled compounds was measured and the efficiency of glycerol-2-3H recovery after the incubation with mitochondria was determined. It was concluded that under the described experimental conditions the formation of cardiolipin in isolated mitochondria takes place according to the reaction mechanism: phosphatidylglycerol + CDP-diglyceride → cardiolipin. Some aspects of these findings are discussed in detail
Studies on the Replication of Polyoma DNA: Physicochemical Properties of Viral DNA Synthesized when Protein Synthesis is Inhibited
Authors: Branton Philip E. , Sheinin Rose
Published: December 2009

Physicochemical, electron microscopic, and enzymatic studies have been carried out to analyze the structure of the polyoma DNA synthesized under conditions in which de novo protein synthesis is inhibited late during infection, and in which (as shown elsewhere) the maturation of progeny viral DNA to yield superhelical, fully covalently closed DNA is blocked. The evidence indicated that viral DNA molecules are accumulated which, upon deproteinization and extraction, give rise to the following: (i) form II Py DNA, double-stranded, circular with one single-strand break; (ii) circular dimers; (iii) form-II-like molecules, but carrying double-stranded, linear "tails".
Thin-Layer Chromatography of Organic Acids
Authors: Beaudoin A. R. , Moorjani S. , Lemonde A.
Published: December 2009

A simple and reproducible method is described for the separation of citric acid cycle intermediates and other related organic acids. The separation is achieved on thin-layer plates (T.L.C.) coated with silica gel H to which magnesium sulfate and sodium carbonate are added. This T.L.C. method ensures clear separation of organic acids. A procedure is also described that permits quantitative recovery of the radioactivity present in citric, glyoxylic, and isocitric acids.
Regulation of Glyconeogenesis from Amino Acids by Acetate in Tetrahymena pyriformis
Authors: Mavrides C.
Published: December 2009

The regulation of glyconeogenesis from amino acids by acetate was studied in Tetrahymena pyriformis. Alanine aminotransferase and glutamate dehydrogenase were repressed by 0.1% sodium acetate in the growth medium. Incorporations into the glycogen of washed cells from the respective isotopically labelled amino acids were similarly suppressed.Incorporations into glycogen from uniformly 14C-labelled L-serine, L-leucine, L-isoleucine, L-tyrosine, and DL-β-14C-tyrosine were also suppressed by prior growth in a medium supplemented with 0.1% or 0.3% acetate. Percentage incorporation into glycogen was highest from tyrosine, followed by leucine, isoleucine, and alanine, and lowest from glutamic acid and serine.Supplementation of the medium with 0.25% glucose resulted in repression of the above two enzymes and suppression of incorporation into glycogen from amino acids.Incorporation of aspartic acid into glycogen was negligible and was variously and minimally affected by growth in glucose- or acetate-supplemented media. Aspartate aminotransferase was affected in a like manner.Glycogen content was not significantly affected by growth in media supplemented with 0.1% or 0.3% acetate. On the whole, the data suggest that acetate spares amino acids for glyconeogenesis by a mechanism which entails repression of amino-acid-catabolizing enzymes.
Amino Acid Metabolism in Plants. IV. Kinetic Studies with a Multispecific Aminotransferase Purified from Bushbean Seedlings (Phaseolus vulgaris L.)
Authors: Forest J. C. , Wightman F.
Published: December 2009

Kinetic studies were carried out on a purified multispecific aminotransferase isolated from bushbean roots. The enzyme was found to catalyze the transamination of L-aspartic and L-glutamic acids, as well as L-phenylalanine, L-tyrosine, and L-tryptophan when α-ketoglutarate or oxaloacetate was provided as the amino group acceptor. The Km values for these substrates and for the substrates of the reverse reactions were determined. Double-reciprocal plots of the data obtained for the initial relative velocities of the different aminotransferase activities indicate that all the transamination reactions catalyzed by this enzyme proceed through a binary complex mechanism. The evidence from competitive inhibition of the aromatic aminotransferase activity by the aliphatic substrate, L-aspartic acid, confirmed the view that only one enzyme is responsible for catalyzing the transamination reactions observed with this purified protein.
Relationship Between Catalytic Activity, Crystalline State, and Environment of the Coenzyme in Phosphorylase a
Authors: Honikel K. O. , Madsen N. B.
Published: December 2009

Muscle glycogen phosphorylase a contains a small proportion of its coenzyme, pyridoxal phosphate, bound in a Schiff base form which absorbs at 415 nm. Excited at this wavelength, it fluoresces with two maxima, 510 nm and 535–540 nm. The ratio of the latter peak height to that of 510 nm varies directly with the specific catalytic activity. Experiments on phosphorylase a with increasing concentrations of imidazole citrate show very similar results. When interpreted in analogy to solvent perturbation effects on model compounds, this finding suggests that the catalytic efficiency depends on the degree of hydrophobicity of the pyridoxal phosphate environment, and provides one more link between the coenzyme and the catalytic process.A single large crystal of phosphorylase a, when excited at 330 nm, exhibits nearly half of its fluorescence emission at 415 nm and the remainder at 510–535 nm, whereas in solution only a small amount of fluorescence is seen at 415 nm. Furthermore, decreasing the temperature of the crystal increases the proportion of fluorescence emission at 415 nm. These results are interpreted on the basis of the hypothesis that the coenzyme is bound in the form of a carbinol amine, absorbing at 330 nm, which is split on excitation to form a Schiff base which emits as such at 535 nm. The crystal structure of the protein requires more energy to effect the transition to the Schiff base, so that a large proportion of the coenzyme molecules fluoresce as the carbinol amine form, while decreasing the temperature increases this proportion even further.
The pH-Induced Transition of Iodinated Ferricytochrome c: Electron Paramagnetic Resonance and Absorption Spectra
Authors: Morton R. A.
Published: December 2009

The heme-associated, pH-induced transition in iodinated ferricytochrome c has been studied by electron paramagnetic resonance (E.P.R.) and absorption spectroscopy. The conversion from type III to type IV (as defined by Theorell, H., and Åkesson, Å.: J. Am. Chem. Soc. 63, 1812 (1941)) ferricytochrome c forms was dramatically altered by iodination of tyrosyl residues. Both absorption and E.P.R. spectra suggested that a transition between similar heme-iron coordination structures occurred with a pK of about 6 as compared with about 9 for native ferricytochrome c. At pH 4.4 the E.P.R. spectrum (liquid nitrogen temperature) of a frozen solution of iodinated ferricytochrome c was similar to the native type III at pH 7, except for an increased g = 6.0 signal from high-spin heme iron. At neutral pH the E.P.R. spectrum of the iodinated derivative was similar to type IV ferricytochrome c. The results give further support to the hypothesis that the pK of tyrosine 67 plays an important role in determining the pK of the III to IV transition.
Enzyme Activities During Culturing of Fetal Rat Liver
Authors: Kirby Lorne , Hahn Peter
Published: December 2009

Liver from fetal rats was cultured in a simple medium. In such cultures tyrosine transaminase (TTA) activity had increased after 20 min and reached twice the initial value within 2 h. Phosphoenolpyruvate earboxykinase (PEPCK) activity decreased during culturing. Incubation of microsomes from fresh fetal liver with dibutyryl cyclic AMP (DcAMP), oleic acid, or acetyl-CoA led to an increase in their TTA activity. It is suggested that the early rise in TTA during culturing is due to release of the enzyme from the microsomal fraction. In contrast to human fetal liver, oleic acid did not induce PEPCK in rat fetal liver cultures. In neither species was there an effect of DcAMP on the amount of fatty acids in the culture medium or on the activities of carnitine acetyl- and carnitine palmitoyltransferases.
Chain Termini of the Satellite RNA from Yeast Ribosomes
Authors: Oakden K. M. , Lane B. G.
Published: December 2009

(1) When yeast cells are extracted with aqueous phenol and the aqueous phase is made 2.5 M with respect to NaCl at 0°, there is selective precipitation of about 80% of the total RNA. The 17 S and 26 S RNA from yeast ribosomes comprise a preponderant mass-fraction (ca. 90%) of this NaCl-insoluble RNA. A small amount (ca. 3%) of a rapidly migrating electrophoretic component (iRMEC) can be released by aqueous denaturation of yeast NaCl-insoluble RNA (iRNA), and because it forms a specific complex with 26 S RNA, this iRMEC component can be appropriately described as a "satellite" of 26 S RNA.(2) Following its release by aqueous denaturation of yeast NaCl-insoluble RNA, the satellite RNA has been subjected to end-group analysis, and it has been found to have a formal structure that is based on a repeating 5′-mononucleotide unit, i.e. (pN)n, where n = 160–200. On the basis of an analysis of its principal termini, the dominant form of the satellite RNA is[Formula: see text](3) In an allied study, a "rapidly labelled" fraction of yeast NaCl-insoluble RNA has been subjected to aqueous denaturation and end-group analysis.
Temperature-Dependent Transition in L-Histidine Ammonia-Lyase
Authors: McClard Ronald W. , Kolenbrander Harold M.
Published: December 2009

The effects of temperature on the energy of activation, the enthalpy of binding, and the apparent equilibrium constant for the overall reaction catalyzed by L-histidine ammonia-lyase (EC 4.3.1.3) have been determined. A temperature-dependent transition (at approximately 30°) involving multiple forms of the enzyme is also discussed.The enthalpy of binding is exothermic above 30° and endothermic below this transition temperature. In addition, a bend is observed in the Arrhenius plots at approximately 34°. The combination of these effects suggests the existence of at least two forms of the enzyme.
Partial Purification and Characterization of RNA Polymerase from Nuclei of Ehrlich Ascites Tumor Cells
Authors: Blair D. G. R. , Mukherjee A. K.
Published: December 2009

DNA-dependent RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase) was partially purified from nuclei of Ehrlich ascites tumor cells by the techniques of sonic disruption in the presence of 0.3 M ammonium sulfate, ultracentrifugation, salt fractionation, and dialysis. The purified enzyme had an absolute requirement for DNA and was inhibited by actinomycin D and other known inhibitors of DNA-dependent RNA polymerase, but not by rifamycin or rifampicin. The four ribonucleoside triphosphates and Mn2+ ions were also required for optimal activity. Optimal concentrations for Mn2+ and Mg2+ ions and (NH4)2SO4 were 2.4 mM, 6.0 mM, and 0.05 M, respectively. All the native and heat-denatured DNA's that were tested served as templates, but the relative activities with the two forms of DNA depended upon the composition of the reaction medium. Of the natural RNA's and 11 synthetic homo- and heteropolyribonucleotides that were tested, the RNA's, poly(A), poly(A,U), and poly(A,C) were slightly active, but less than 5% as efficient as calf thymus native DNA, with 3H-UTP as the labeled substrate.
The Microheterogeneity of Human Haptoglobin and Its Complex with Hemoglobin
Authors: Yang H. J. , Przybylska M.
Published: December 2009

Human haptoglobin, type 1S-1S, isolated from plasma and from ascites fluid was subjected to isoelectric focusing in polyacrylamide gel and its complex with horse cyanomethemoglobin was analyzed by isoelectric focusing in a column using a sucrose density gradient. Both methods revealed microheterogeneity. Similar patterns were obtained consisting of five to eight strong bands with a symmetrical distribution giving the highest yield in the center. An investigation of the nature of these bands was carried out and it was found that the sialic acid content varied in the different components. Experiments were undertaken to show that the multiple bands were not due to the binding of Ampholine to the protein and that this heterogeneity preexisted in haptoglobin prior to its isolation. No observable difference in heterogeneity was observed between samples of haptoglobin isolated by different methods and for complexes obtained by adding hemoglobin to haptoglobin and haptoglobin to hemoglobin.The unfractionated complex and the separated complex components were crystallized.
Studies on Horseradish Peroxidase. XIII. The Kinetic Effect of Cyanide on the Oxidation–Reduction Cycle
Authors: Cotton M. L. , Dunford H. B. , Raycheba J. M. T.
Published: December 2009

The effect of cyanide on the steady-state oxidation of ferrocyanide by horseradish peroxidase was studied at pH values 9.00, 7.10, and 5.00. An inhibition was observed which could be explained by the binding of cyanide only to native horseradish peroxidase. Spectra in the Soret region supported these conclusions.
Thymidine as One of the Factors in a Beef Liver Extract Decreasing 3H-thymidine Incorporation into DNA
Authors: Lenfant M. , Kren-Proschek L. , Verly W. G. , Dugas H.
Published: December 2009

Gel filtration (Sephadex G-15) of a beef liver extract has revealed two peaks having inhibitory action on 3H-thymidine incorporation into the DNA of regenerating rat liver slices. Peak I seemed to contain a factor specific for hepatic tissues, which might be the liver chalone, whereas the activity of peak II was due to the presence of thymidine.
Binding of the Nucleoside Transport Inhibitor 4-Nitrobenzylthioinosine to Erythrocyte Membranes
Authors: Pickard M. A. , Brown R. R. , Paul B. , Paterson A. R. P.
Published: December 2009

4-Nitrobenzylthioinosine (NBMPR), a potent nucleoside transport inhibitor, was prepared in two radioactive forms and the binding of these to erythrocyte ghosts was studied. Similar binding data were obtained with inhibitor containing 14C in the purine 8-position or in the benzyl 7-position, suggesting that the entire inhibitor molecule was bound. A saturable high-affinity mode of NBMPR binding was apparent; NBMPR bound in this way was not removed by washing, but was displaced by a related inhibitor of nucleoside transport, 2-hydroxy-5-nitrobenzylthioguanosine (HNBTGR). It is postulated that the high-affinity binding sites are the nucleoside transport elements of the erythrocyte membrane. From ghosts treated with 14C-NBMPR under conditions which assured binding of the high affinity type, 14C was recovered by extractions in the form of NBMPR. Thus, this mode of NBMPR binding is reversible and covalent linkages do not appear to be involved. A low affinity mode of NBMPR binding was also demonstrated; this appeared to be a partition of NBMPR between the medium and the membrane substance. This component of bound NBMPR was not displaced by HNBTGR and was removed by washing.
14C-Phenylalanine Incorporation by Wheat-Seedling Cytoplasmic Ribosomes
Authors: Tucker Edward B. , Zalik Saul
Published: December 2009

14C-phenylalanine incorporation was induced by wheat-seedling cytoplasmic ribosomes which had been isolated by zonal centrifugation. The incorporation was optimal with high concentrations of these 80 S ribosomes, high concentrations of magnesium, and low concentrations of Tris–HCl buffer, pH 7.6, and was complete after 45 min of incubation at 37 °C. This transfer of 14C-phenylalanine from 14C-phenylalanyl-tRNA into protein was not dependent upon added energy factors or poly U. A puromycin pretreatment aided dissociation of the cytoplasmic ribosomes into subunits. The reformed parent species did not support polyphenylalanine synthesis.
Ribonucleic Acid Polymerase Induced in L-Cells Infected with Vesicular Stomatitis Virus
Authors: Galet Helene , Shedlarski Jr. Joseph G. , Prevec Ludvik
Published: December 2009

RNA polymerase activity capable of synthesizing long-chain, heteropolymeric RNA is associated with specific ribonucleoprotein complexes present in the cytoplasm of cells infected with vesicular stomatitis virus (VSV). The synthesis is independent of added exogenous template and the product labelled with GTP precursors can be totally annealed with excess virion RNA. The enzyme activity is therefore a transcriptase similar to that observed in association with the mature VSV virion.
Modification de Conformation des Sous-unités Ribosomiques 30 S en Relation avec L'activité de la Streptomycine : Etude par Fluorescence
Authors: Lenfant Maryse , Forget Adrien
Published: December 2009

Ethidium bromide (ETB) has been bound to the 30 S ribosomal subunits of both a streptomycin (Sm-CHO) sensitive and resistant strain of E. coli. The fluorescent intensity of the complex ETB – 30 S sensitive subunit is higher than that of the complex ETB – 30 S resistant subunit. When the 30 S sensitive subunit is previously treated with Sm-CHO, the intensity of the ETB – 30 S sensitive subunit complex is reduced. In contrast, the pretreatment of the 30 S resistant subunit by Sm-CHO does not affect the fluorescence of the dye complex. In addition no perturbation of the fluorescent complexes can be noted when either the 30 S resistant or 30 S sensitive subunit was pretreated with streptomycine oxime (Sm-CH=NOH), a biologically inactive derivative of Sm-CHO. These results indicate that the accessibility of the dye to the base-paired region of the 16 S RNA, the target of ETB, has been modified as resistance is conferred to the 30 S subunit.The modification of the quaternary structure of the 30 S resistant subunits as shown by fluorescence is similar to the Sm-CHO modification of the pretreated 30 S sensitive subunit.
Role of Methionine in the Initiation of the Biosynthesis of Bovine Proinsulin
Authors: Yip C. C. , Liew C. C.
Published: December 2009

Slices of fetal bovine pancreas were used to study the initiation of proinsulin biosynthesis. The pancreatic slices were incubated with radioactive methionine, phenylalanine, or leucine, in a defined medium. The incorporation of amino acid into peptides in the tissue slices was measured for 2–3 h. Two types of radioactive peptides, "free" and "blocked," were identified by ion-exchange chromatography. Most of the radioactive "blocked" peptides labelled with [3H]phenylalanine and [35S]methionine were hydrolyzed by proteases, except for about 20% of those labelled with [35S]methionine, which also showed higher resistance to acid hydrolysis.Microsomes were isolated from the tissue slices after incubation and were extracted with acid alcohol. The radioactive proteins in the extract were reacted with a solid immunosorbant against insulin. Analysis of the immunoadsorbed radioactive peptides by Edman degradation showed the presence of both methionine and phenylalanine as the N-termini. It was concluded that methionine was an initiating amino acid in the biosynthesis of bovine proinsulin.
Dog Kidney Phospholipids and the Question of Renin Inhibition
Authors: Tinker D. O. , Schwartz H-J. , Osmond D. H. , Ross L. J.
Published: December 2009

We have investigated renin inhibitory activity in relation to the chemical composition of several phospholipids, especially those isolated from an organic fraction of dog kidneys reported to contain a phosphatidyl amino acid renin 'preinhibitor'. In our hands, this fraction, eluted from a silicic acid column with chloroform–methanol (4:1), contained large amounts of phosphatidylthanolamine (PE) as established by infrared spectroscopy, silica gel, paper, and gas–liquid chromatography, elemental analysis, and specific stains. No other ninhydrin-positive phospholipid migrating as 'preinhibitor' on thin-layer chromatographs was detected, with the possible exception of a very minor, unidentified, ethanolamine-positive component. Also eluted with the PE was lyso PE, in a quantity (0.16 mg/g kidney) within the range originally reported for 'preinhibitor'. But coidentity of 'preinhibitor' and lyso PE is unlikely since the latter is deacylated, contains ethanolamine and a much higher percentage (66 mol %) of arachidonate in its esterified fatty acids, and does not inhibit renin in vitro. Dog and rat kidney PE, and, most potently, ox brain phosphatidylserine, all inhibited renin in vitro, but not in vivo. These data argue against the existence and proposed structure of the renal renin 'preinhibitor', and also against the concept of a unique inhibitory role of a specific base moiety and fatty acid composition. Lack of in vivo renin inhibition using the infusion technique by which such inhibition was originally demonstrated questions the relevance of the tested phospholipids as physiological regulators of the rennin–angiotensin system.
Interrelationship Between Serum β-Lipoprotein and Cholinesterase
Authors: Kutty K. M. , Rowden G. , Cox A. R.
Published: December 2009

The possible association between serum β-lipoproteins and cholinesterase was investigated in vivo after artificial induction of hyperlipidemia in rabbits, resulting from the injection of the lipopolysaccharide of Escherichia coli (E. coli endotoxin), and in vitro by following the action of phospholipase D upon isolated human serum β-lipoprotein.A marked increase in serum pre-β-lipoproteins (VLDL) was found to occur within 24 h after the injection of E. coli endotoxin in rabbits. In the next 48–72 h, a marked reduction in pre-β- (VLDL) concomitant with a marked increase in β- (LDL) and α- (HDL) lipoproteins was observed. A sharp increase in cholinesterase isoenzyme activities was visualized (starch gel zymogram) with the development of hyper-pre-beta-lipoproteinemia and decrease with hyper-beta-lipoproteinemia.When isolated serum β-lipoproteins were incubated with phospholipase D for 24 h at 37 °C, release of cholinesterase associated with a decrease in β-lipoprotein concentrations along with the formation of a lipoprotein with a pre-beta mobility was noticed.These observations suggest that cholinesterase is intimately associated with the structure of β-lipoprotein and the point of association of the enzyme is likely to be at the phosphoryl choline site of the lipoprotein molecule.
Effect of Adrenalectomy and of Adrenocortical Hormones on RNA Turnover in a Variety of Subcellular Fractions of Rat Liver
Authors: Mishra R. K. , Feltham L. A. W.
Published: December 2009

(1) The turnover of RNA was examined by following the loss of radioactivity after a single injection of 14C-orotic acid in nuclei, mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, free polysomes, total ribosomes, and sRNA from rat liver. The half-lives of the RNA of various rat liver fractions were found to be 8.7, 6.5, 6.4, 5.4, 4.4, 4.9, and 4.8 days, respectively.(2) In adrenalectomized rats there was a significant decrease in turnover rate. This suggests a slower synthesis of RNA under steady-state conditions. The corresponding values were 12.0, 8.5, 6.5, 6.9, 5.8, 6.1, and 5.9 days.(3) Daily administration of corticosterone or hydrocortisone to adrenalectomized rats restored the turnover rate to normal. Aldosterone was without effect.(4) Aggregate RNA polymerase of rat liver nuclei was decreased by adrenalectomy and restored by corticosterone or hydrocortisone. Aldosterone was without effect.
Polyprenols of Listeria monocytogenes
Authors: Vilim A. , Woods M. C. , Carroll K. K.
Published: December 2009

Listeria monocytogenes was found to contain polyprenols in a concentration of 215 mg/kg of lyophilized bacteria. They consisted mainly of undecaprenol with a small amount of decaprenol. Characterization by infrared, nuclear magnetic resonance, and mass spectroscopy indicated that the undecaprenol had the same structure as that isolated from other bacteria.
An Improved Method for the Preparation of Isomeric α,ε-Diaminopimelic Acid from Glutaraldehyde
Authors: Roy R. B. , Karel M.
Published: December 2009

An aqueous solution of glutaraldehyde was reacted with a mixture of sodium cyanide and ammonium chloride giving a high yield of 2,6-dicyanopiperidine. Refluxing of this compound with a mixture of ammonium hydroxide and ammonium bicarbonate produced 5,5′-trimetbylene dihydantoin, which on acid hydrolysis gave α,ε-diaminopimelic acid.
Two Isoaccepting Species of Tryptophan Transfer Ribonucleic Acid from Chlamydomonas reinhardii
Authors: Freddie D. L. , Freddie E. C. , Guerrini A. M. , Cremona T.
Published: December 2009

Two isoaccepting species of tryptophanyl-tRNA have been isolated from the green alga Chlamydomonas reinhardii One species, the first to be eluted from a methylated albumin–kieselguhr column, resembles the tryptophanyl-tRNA from Escherichia coli described by Gartland and Sueoka (Proc. Natl. Acad. Sci. Wash. 55, 948 (1966)) and Ishida and Sueoka (J, Mol. Biol 37, 313 (1968)), in that it can be interconverted to and from form I and form II. The second species does not interconvert and appears to be chemically different from the first species.
The Glyoxylate Cycle in Germinating Ginkgo biloba Seeds
Authors: Vanni P. , Mastronuzzi E. , Vincenzini M. T. , Firenzuoli A. M.
Published: December 2009

The high level of lipids in Ginkgo biloba seeds suggested that the glyoxylate cycle is operative during germination. The correlation between the lipid content of germinating seeds and the key-enzyme levels of the cycle were studied. The fatty acid composition and content of the triglyceride fraction during germination were also investigated.
Synthesis and Kinase Phosphorylation of 4-Deoxy-D-threohexulose
Authors: Haylock Clifford Raymond , Slessor Keith Norman
Published: December 2009

Synthesis of the only unknown deoxyfructose, 4-deoxy-D-threohexulose, is reported. Its preparation involved reductive lithium aluminum hydride ring opening of 3,4-anhydro-1,2:5,6-di-O-isopropylidene- D-talitol, followed by hydrolysis of the resulting epimeric deoxy diisopropylidene hexitols and selective Acetobacter suboxydans oxidation of 3-deoxy-D-arabinohexitol. Kinetic studies using 4-deoxy-D-threohexulose as substrate for yeast hexokinase support the premise that the C-4 hydroxyl is a binding group in formation of the enzyme–substrate complex. Enzymatic synthesis of 4-deoxy-D-threohexulose 6-phosphate and 4-deoxy-D-threohexulose 1,6-diphosphate has been achieved in low yield from 4-deoxy-D-threohexulose.
The Effects of Protein on Lipid Organization in a Model Membrane System: A Spin Probe and X-Ray Study
Authors: Butler K. W. , Hanson A. W. , Smith Ian C. P. , Schneider H.
Published: December 2009

The role of proteins and polypeptides in controlling the orientation of lipid molecules in bilayers was investigated by spin probe and X-ray diffraction techniques. Only when proteins and polypeptides had a net positive charge was a marked effect noted on molecular orientation within brain lipid films. Several proteins and polypeptides exerted an effect similar to that of salts leading to the formation of planar parallel multibilayers with the long axis of the spin probe oriented close to the normal to the plane. Others produced broad angular distributions of the probe within the multilayers. This latter effect took place even in the presence of inorganic ions, which by themselves tend to orient the probes perpendicular to the lamellar plane. The nonpolar residues of the polypeptides are thought to produce disorder by interdigitating with the lipids.
An Endonuclease for Depurinated DNA in Rat Liver
Authors: Verly W. G. , Paquette Y.
Published: December 2009

Rat liver contains an endonuclease which breaks DNA strands near apurinic sites. The purified enzyme is strictly specific for apurinic sites; it has no action on DNA normal strands, or on strands carrying alkylated sites. These properties are identical to those of the Escherichia coli endonuclease for depurinated DNA.
Observations on the Relationship of Hepatic Choline Uptake to Ethanolic Fatty Liver in the Rat
Authors: Mendenhall Charles L. , Wilson Norman L.
Published: December 2009

Because ethanol ingestion is known to produce an accumulation of hepatic triglycerides and hence an increased need for lipoprotein production, it has been suggested that increased hepatic utilization of choline occurs as a secondary phenomenon resulting from an increased need for choline-containing phospholipids utilized for lipid–protein binding in lipoprotein formation. To evaluate this, rats given radiotagged choline were sacrificed at varying time intervals after acute ethanol ingestion. As expected, an increase both in hepatic radiotagged choline uptake (mean 146%) and a total hepatic triglycerides (mean 285%) was observed. However, radiotagged choline uptake occurred very rapidly and was maximal at 2 h whereas triglycerides accumulated more slowly with the greatest values seen at 16 h when no ethanol effect on choline uptake was observed. These data indicate that no causal relationship exists between ethanol-stimulated hepatic choline uptake and triglyceride accumulation. Other explanations are suggested.
Relative Activities of Acetyl-CoA Carboxylase and Fatty Acid Synthetase in Chick Liver: Effects of Dietary Fat
Authors: Liou Gregory I. , Donaldson W. E.
Published: December 2009

The specific activities of acetyl-CoA carboxylase and fatty acid synthetase were measured in the cytosol fraction of livers from chicks fed various levels of corn oil, cottonseed oil, corn-oil free fatty acids, or crude (79%) oleic acid. Activities of both enzymes were depressed by the addition of fat to a fat-free basal diet. The ratios of synthetase to carboxylase activity were greater than unity when up to 4% fat was fed, but less than unity when 8% or higher levels of fat were fed. The depressions of the activities of these enzymes appeared to be unrelated to the dietary level of linoleate. In in vitro experiments, 2 μM concentrations of palmityl-CoA or oleoyl-CoA depressed acetyl-CoA carboxylase activity. Concentrations of 20 μM of these acyl-CoA esters did not affect the activity of fatty acid synthetase.
A Comparison of Diphosphonoglyceric Acid and Diphosphoglyceric Acid as Allosteric Effectors for Hemoglobin
Authors: Benesch Ruth E. , Benesch Reinhold , Yung Suzanna , Baer Erich , Robinson Ranga
Published: December 2009

2,3-Diphosphoglycerate is the major intraerythrocytic cofactor for oxygen release by hemoglobin. The phosphono analogue, 2,3-diphosphono-DL-glyceric acid, has only minimal effects on the oxygen affinity of hemoglobin. This finding is readily understood in terms of the electrostatic and spatial requirements of the binding site in deoxyhemoglobin.
A Human IgG Myeloma Protein Crystallizing with Rhombohedral Symmetry
Authors: Connell G. E. , Freedman M. H. , Nyburg S. C. , Painter R. H. , Parr D. M. , Pinteric L. , Pruzanski W.
Published: December 2009

The M-component in the serum of a patient with multiple myeloma and hyperviscosity syndrome was found to be an immunoglobulin of the IgG-1(K) class which crystallized spontaneously from the serum. After purification, the protein crystallized readily under a variety of conditions. X-ray diffraction studies indicated a rhombohedral lattice with cell dimensions: aR = 170 ± 5 Å, αE = 109 ± 2°. Assuming a molecular weight of 1.5 × 105, the crystals have been calculated to contain 66 ± 3% solvent, and six molecules per unit cell.Screening of the protein for antibody-like activity against a wide range of antigens gave positive results in several instances, in particular when tested against gum Karaya. This reaction was inhibited by D-glucuronic acid.
α-Foetoprotein: Purification on Sepharose-linked Concanavalin-A
Authors: Page Michel
Published: December 2009

Using serum obtained from human cord blood α-foetoprotein was purified by batch fractionation on DEAE-Sephadex A-50 followed by a single passage through a Sepharose-linked Concanavalin-A column. A 360-fold purification factor was obtained by this two step procedure.