bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the mechanism of action of ethylene. II. Effects of ethylene on mitochondria from rat liver and yeast, and on mitochondrial adenosine triphosphatase
Authors: Olson A. O. , Spencer Mary
Published: December 2009

Ethylene treatment of rat liver and yeast mitochondria was found to increase the rate of mitochondrial volume change caused by adenosine diphosphate or adenosine triphosphate. As well, ethylene increased the rate of adenosine triphosphate hydrolysis by mitochondria from rat liver, yeast, and bean cotyledons. However, the gas had no effect on the reactivity of a partially purified adenosine triphosphatase prepared from mitochondria of rat liver or bean cotyledon. For ethylene to exert its effect, it appears that the enzyme must be in its natural locale in the mitochondrial membrane, where the gas can accumulate in relatively high concentrations. The effects of ethylene on respiration in vivo are explicable on the basis of these observations.
Plasma esterase and acid ribonuclease following the injection of heparin in dogs
Authors: Levy S. W.
Published: December 2009

Heparin, 1.5–4.0 mg/kg, was injected intravenously into dogs. Increases were observed regularly in the activities of total- and eserine-resistant tributyrin esterase and of acid ribonuclease in the plasma. These occurred 2–15 min following the injection of heparin, remained elevated for 4–5 h, and returned to normal levels within 24 h. Eserine-sensitive esterase declined following the injection and no changes were observed in the activities of acid β-glycerophosphatase, β-glucuronidase, or cathepsin. The results are discussed in terms of the mechanisms of enzyme release following the injection of heparin.
Lipid synthesis in Lipomyces lipofer
Authors: McElroy F. A. , Stewart H. B.
Published: December 2009

The synthesis of lipids by cell-free fractions of Lipomyces lipofer was investigated by measuring the incorporation of acetate-14C and other radioactive precursors into lipid-soluble material. On the basis of cofactor requirements, the reaction to inhibitors, and the ability to incorporate appreciable quantities of malonate-14C, it was concluded that the malonyl-CoA pathway was the principal route of fatty acid synthesis in this yeast. By employing a means of cell dispersion less rigorous than previously used with yeasts, it was shown that the soluble portion (high-speed supernatant) of the cell was primarily involved in lipid synthesis. The mitochondrial fraction and the high-speed pellet (96 000 × g, 1 h) were inactive although the latter fraction was required for the maximum activity of the high-speed supernatant. The stimulatory activity of this pellet was very labile and showed a lag period before it became effective. Several lines of evidence suggested that the carboxylation of acetyl-CoA is the rate-limiting step in lipid synthesis which is accelerated by the high-speed pellet.
Respiration and oxidative phosphorylation by muscle and heart mitochondria of hamsters with hereditary myocardiopathy and polymyopathy
Authors: Wrogemann Klaus , Blanchaer M. C.
Published: December 2009

Mitochondria isolated from skeletal muscle and heart of normal Syrian hamsters and from hamsters of the BIO 14.6 myopathic strain aged 97–124 days were studied. Histological examination of the tissues and serum creatine phosphokinase determinations established that the disease was active in the dystrophic animals. In the mitochondrial isolation procedure the minced tissue was incubated before homogenization in a mannitol–sucrose–EDTA medium containing a proteinase (Nagarse). Polarographic estimations with pyruvate–malate as substrate, in the presence and absence of ADP, indicated that the rate of O2 uptake, ADP/O ratio, and respiratory control ratio (state 3 to 4 transition) of the heart mitochondria did not suffer significantly between the normal and myopathic groups. The findings with the skeletal muscle mitochondria were similar. L-α-Glycerophosphate oxidation also was not affected by the myopathy but the rate of NADH oxidation was 35% slower in the heart mitochondria of the BIO 14.6 strain.
Uptake of 32P-orthophosphate and incorporation into phospholipids in Tetrahymena pyriformis W exposed to phenothiazine derivatives
Authors: Rogers Charles G.
Published: December 2009

Partial inhibition of growth of Tetrahymena pyriformis W by promazine or chlorpromazine resulted in a 60% increase in phospholipid concentration during the exponential phase. Age or drug treatment did not affect the pattern of phospholipids as shown by thin-layer chromatography. At least 8 phospholipid components were recognized, of which phosphatidylethanolamine accounted for almost 50% of the total lipid phosphorus and phosphatidylcholine for about 20%. Uptake of 32P-orthophosphate by resting cells from cultures in the exponential phase was inhibited by chlorpromazine, promazine, promethazine, trifluoperazine, prochlorperazine, acetophenazine, and 2,4-dinitrophenol.Chlorpromazine and 2,4-dinitrophenol differed from one another in their effect on the distribution of 32P-orthophosphate among the principal phosphorus compounds of the cell; in the pattern of labelling of phospholipids with 32P, as shown by autoradiography of thin-layer chromatograms; and in the magnitude of specific activity values for individual phospholipids. These findings showed that the mechanism(s) by which phenothiazine derivatives alter the distribution of absorbed 32P and its incorporation into phospholipids in Tetrahymena differs from that of 2,4-dinitrophenol and that this may be associated with the ability of the tranquilizing drugs to inhibit nutrient uptake by the cells.
Effects of inorganic salts and of ouabain on some metabolic responses of rat cerebral cortex slices to cationic and electrical stimulations
Authors: Nakazawa S. , Quastel J. H.
Published: December 2009

The rate of glycine uptake, against a concentration gradient, into rat brain cortex slices, incubated in a physiological glucose medium, is proportional to the sodium ion concentration of the medium and is independent of whether choline chloride or sucrose is used to balance diminished levels of sodium ions. Choline, in contrast to sucrose, resembles sodium in the maintenance of stimulated brain respiration but cannot replace sodium for the stimulation of brain respiration by electrical impulses or by increased potassium ion concentrations. Electrical stimulation of rat brain slices, whilst resembling potassium stimulation in causing a fall in the level of ATP, differs from potassium stimulation in causing no diminution in the rate of glycine transport. This is considered to be due to the operation of two opposing processes: (a) increased glycine influx due to increased influx of sodium, and (b) diminished glycine influx due to a decreased ATP level.The stimulation of rat brain respiration brought about by the application of electrical impulses or by the presence of high potassium ion concentrations, and the uptake of glycine against a concentration gradient, are controlled by the activity of membrane-bound ATPase. This conclusion is supported by the following facts, (a) The presence of potassium ions is needed to obtain the optimal respiratory responses and the optimal rate of glycine uptake; (b) ouabain inhibits the influx of glycine whether the brain tissue is in the stimulated condition or not and it also inhibits stimulated brain respiration; (c) absence of magnesium ions, or a high concentration of magnesium ions, diminishes the effects of high potassium ion concentration or of electrical stimuli on brain respiration; and (d) high concentrations of calcium ions, which block ATPase, inhibit stimulated brain respiration.
Physicochemical and chemical studies on wheat embryo ribosomal proteins
Authors: Wolfe Fred H. , Kay Cyril M.
Published: December 2009

The physical heterogeneity of unfractionated wheat embryo ribsomal proteins, prepared by the glacial acetic acid method of Waller and Harris, has been investigated in 8 M urea −10−3 M dithio-threitol solutions of low pH (4.5). Sedimentation–diffusion measurements resulted in a weight average molecular weight of 29 000 ± 2 500, with no obvious evidence of heterogeneity. High-speed membrane osmometry was employed to establish the number average molecular weight of this system as 24 500 ± 1 000. The disparity in molecular weight averages suggests some size heterogeneity, and statistical analysis based on the two average molecular weights resulted in a calculated range of molecular weights for wheat embryo ribosomal proteins from 15 000 to 34 000 a.m.u. Charge differences, reflecting presumably primary structure differences, also exist among the members of this class, since about 26 different bands were resolved on polyacrylamide gel electrophoresis. The weight intrinsic viscosity of the ribosomal proteins in 8 M urea solutions was established as 0.273 dl/g, a value considerably larger than most globular proteins, suggesting that a major portion of their polypeptide chains are unfolded in this solvent. This conclusion was substantiated by optical rotatory dispersion measurements on this system, which resulted in a dispersion constant, λc, of 213 m μ, a value typical of that of the random coil. Amino acid and N-terminal analyses are also reported for this system, and comparisons of both chemical and physicochemical parameters are made with ribosomal proteins of other sources.
Isolation and some properties of argininosuccinate lyase from a higher plant source
Authors: Shargool P. D. , Cossins E. A.
Published: December 2009

L-Argininosuccinate arginine-lyase (EC 4.3.2.1) was extracted from the cotyledons of germinating pea seeds. The enzyme was purified approximately 20 times by isoelectric precipitation, followed by treatment with calcium phosphate gel and chromatography on carboxymethyl cellulose. The partially purified enzyme was shown to catalyze both the condensation of arginine and fumarate to give argininosuccinate and the cleavage of argininosuccinate to give arginine and fumarate. The enzyme displayed maximal activity at pH 7.9 and was relatively stable after storage at −20 °C for 12 months or after dialysis overnight at 2 °C. The Michaelis constants for argininosuccinate and arginine were found to be 2 × 10−4 M and 6.7 × 10−3 M respectively. Enzyme activity was partially inhibited by 10−4 M p-chloromercuribenzoate. It is concluded that this enzyme has importance in arginine biosynthesis in germinating pea cotyledons.
Culture methods and detection of glucanases in suspension cultures of wheat and barley
Authors: Gamborg Oluf L. , Eveleigh D. E.
Published: December 2009

Suspension cultures of Triticum monococcum L., Triticum vulgare Vill. var. Thatcher, Hordeum vulgare L. var. Gateway, and Hordeum vulgare L. var. Gateway mutant yv2 have been established. The cultures were derived from root sections of seedlings and cultured in a denned medium consisting of mineral salts, sucrose, B vitamins, and 2,4-dichlorophenoxyacetic acid, with nitrate and ammonia as the sources of nitrogen. In the early period of the cultures the cell aggregates readily, differentiated to form roots, but this characteristic diminished after several generations of subculture. The cells and medium contained a number of glucanases. The presence of a laminaranase (endo-β-(1 → 3)-D-glucan glucanohydrolase (EC 3.2.1.99)) that did not attack lichenan was established. The culture media of the wheat contained an oligosaccharide which on acid hydrolysis yielded galactose, arabinose, and xylose. Hydrolysis of a cell-wall fraction yielded the same sugars in addition to glucose and mannose.
The metabolism of the erythrocyte. XVIII. Inhibition of nucleotide synthesis in human erythrocytes by adenosine
Authors: Manohar S. V. , Lerner M. H. , Rubinstein D.
Published: December 2009

Incubation of human erythrocytes with glucose and 1.5 mM adenine for 12 h doubles the intracellular level of ATP because of synthesis of the nucleotide from the purine. The effect of the nucleosides inosine, guanosine, and adenosine on the synthesis of nucleotide labile phosphate during the incubation was studied. Inosine and guanosine had no effect, but adenosine, in concentrations between 10 and 20 mM, inhibited the increase in labile phosphate and the incorporation of adenine-8-14C into ATP. The adenosine has no effect on the slight incorporation of adenine-8-14C into, or the intracellular concentration of, ADP or AMP. The inhibition is not due to the formation of ammonia and (or) inosine resulting from the deamination of adenosine, nor is it due to the change of pH produced by the ammonia. Adenosine must be present to produce its inhibitory effect and the inhibition can be reversed by removal of the nucleoside, either by washing the cells or through the action of the erythrocyte adenosine deaminase. It thus appears that adenosine produces its effect when it is present in concentrations too great to be completely deaminated. A small proportion (0.5%) of the added adenosine is incorporated into the cellular nucleotides, more than half into IMP, resulting in a marked increase in the concentration of this nucleotide. It is suggested that adenosine acts by inhibition of the synthesis of either 5-phosphoribosyl-1-pyrophosphate or adenylic acid.
Sulfur-oxidizing enzyme of Ferrobacillus ferrooxidans (Thiobacillus ferrooxidans)
Authors: Silver Marvin , Lundgren D. G.
Published: December 2009

The sulfur-oxidizing enzyme was purified about 15-fold from sulfur-grown Ferrobacillus ferrooxidans. The enzyme has a pH optimum of 7.8 and requires both elemental sulfur and reduced glutathione (GSH); however, a glutathione–polysulfide complex could also serve as substrate. The Km for GSH was determined to be 2 × 10−3 M. Non-heme iron and labile sulfide were present in the enzyme preparation, and sulfite was found to be the end product of the reaction.
11-Dehydrocorticosteroids in tissues of mice
Authors: Burton A. F. , Turnell R. W.
Published: December 2009

Mice were injected with 14C-corticosterone or 14C-cortisol, or tissues were incubated with these compounds and extracts were chromatographed on paper. Most radioactivity was recovered as the unchanged steroid and its 11-dehydro metabolite. In vitro formation of 11-dehydrocorticosterone was similar in lung, brain, thymus, spleen, and muscle, while kidney was tenfold greater. The percentage of 11-dehydrocorticosterone found in tissues from injected mice ranged from 1.8 to 13 (average 5.3) in the less active tissues and 41% in kidney. Metabolites formed by kidney were reduced by liver in vitro. In blood the percentage of 11-dehydrocorticosterone after passage through the kidney rose from 1.9 to 5.6, and that of cortisone from 2.0 to 8.2. The values for blood passing through the liver decreased from 7.2 to 4.0 for 11-dehydrocorticosterone and from 6.7 to 2.9 for cortisone. Several 11α-hydroxysteroids injected at a dosage 10 times the 14C-steroid reduced by half the 11-dehydrocorticosterone or cortisone in kidney, but did not lessen the thymolytic action of cortisone when administered simultaneously. It was concluded that the level of 11-dehydrocorticosteroids found in tissues bears some relationship to the 11β-hydroxysteroid dehydrogenase activity of those tissues and can be lowered by inhibitors of the enzyme. The kidney is a very active site of dehydrogenation, but the liver reduces the metabolites at a comparable rate thereby maintaining the level of active hormone in the general circulation.
Biosynthesis of valinomycin
Authors: MacDonald J. C. , Slater G. P.
Published: December 2009

A Streptomyces species (PRL 1642) was grown on media containing compounds labeled with 14C or 15N. Valinomycin was isolated from the cultures and degraded to show the distribution of the isotopes. D-α-Hydroxyisovaleric-1-14C acid was incorporated specifically into the D-α-hydroxyisovaleryl portion of valinomycin, and the L-isomer was not incorporated. L-Valine-15N-1-14C was incorporated to a similar extent into the D- and L-valyl portions of valinomycin, and into mycelial valine. L-Lactyl-L-valine-114C was not incorporated directly into valinomycin but was probably first hydrolyzed to L-valine.
Visible, optical rotatory dispersion, and paramagnetic resonance spectra of the L-histidine–Cu(II)–L-threonine complex
Authors: Sarkar Bibudhendra , Bersohn Malcolm , Wigfield Yuk , Chiang Teh-Ching
Published: December 2009

The stability constant of L-histidine-Cu(II)-L-threonine relative to Cu(II)-L-histidine and Cu(II)-L-threonine has been determined. The absorption maxima of Cu(II)-L-histidine and Cu(II)-L-threonine were shown to be at 645 mμ and 625 mμ respectively and a solution containing a mixture of L-histidine, Cu(II), and L-threonine in a 1:1:1 molar ratio shows an absorption maximum at 615 mμ. Shifts in absorption spectra and changes in the optical density were observed when the relative concentration of the ligands in the mixture was changed. The optical rotatory dispersion studies reveal that, in the region 640–700 mμ, it is especially apparent that the molar rotation of the mixed solution is by no means an average of the molar rotation of the Cu(II)-L-histidine and Cu(II)-L-threonine complexes. The three complexes show a close overall similarity of the electron paramagnetic resonance (EPR) parameters. The EPR spectrum of cupric complexes in the mixed solution resembles both the L-threonine and L-histidine complexes in its main features but it differs in significant detail from each of them. The hyperfine splitting of the mixed complex in solution is evidently greater than that of either the Cu(II)–L-histidine or Cu(II)–L-threonine. A structure for L-histidine–Cu(II)–L-threonine is proposed.
The sulfhydryl groups of muscle phosphorylase. I. Number and reactivity
Authors: Battell M. L. , Smillie L. B. , Madsen N. B.
Published: December 2009

The sulfhydryl groups of glycogen phosphorylase from rabbit muscle have been investigated with respect to their reactivity with p-chloromercuribenzoate (PCMB), 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB), cystine, N-ethylmaleimide (NEM), iodoacetic acid, and iodoacetamide. By spectrophotometric titration, PCMB reacts with 6 of the 18 half-cystine residues in native phosphorylase b, and with 12–14 of the 36 half-cystine residues in native phosphorylase a, and causes complete inactivation in both cases. Reaction of approximately 6 more residues in phosphorylase b (12 in phosphorylase a) occurs when the protein is denatured with HCl or sodium dodecyl sulfate (SDS).DTNB, cystine, and iodoacetic acid react with only two sulfhydryl groups in native phosphorylase b, and do not cause any loss of activity. Iodoacetamide can also react with two sulfhydryl groups without causing any loss of enzymic activity, but activity is lost in proportion to the extent of titration of the next four groups. DTNB reacts with 12 groups in SDS-denatured phosphorylase b but with only 9 groups in urea- or guanidine HCl-denatured enzyme. NEM and iodoacetic acid react with 14 groups in urea-denatured phosphorylase b. Two experiments are reported that provide additional confirmation of previous reports of the absence of disulfide bridges in phosphorylase.We conclude that two sulfhydryl groups per mole of phosphorylase b can react with any reagent without loss of enzymic activity. When the correct reagent and conditions are chosen, a further class of four sulfhydryl groups reacts, resulting in complete loss of enzymic activity. Thus, only two specific sulfhydryl groups on each monomer unit need be titrated to inactivate glycogen phosphorylase and cause it to dissociate. Upon denaturation of phosphorylase by several of the usual protein denaturants, another class of sulfhydryl groups reacts readily, the exact number depending on the reagent and the conditions, but the complete titration of all 18 sulfhydryl groups per molecule of phosphorylase b occurs only under special conditions. These results are of general relevance to procedures employing various protein denaturants and sulfhydryl reagents for the titration of protein sulfhydryl groups.
The oxidation of β-lactoglobulin in sodium dodecyl sulfate solutions
Authors: Leslie James , Varricchio Frederick
Published: December 2009

The rate of oxidation of β-lactoglobulin with ferricyanide decreases markedly as the concentration of sodium dodecyl sulfate is increased from 0.25 to 1.0%, whereas the detergent concentration has little effect on the rate of oxidation of this protein by o-iodosobenzoate and 2,6-dichlorophenol indophenol. It is suggested that the structure of this protein in sodium dodecyl sulfate, coupled with the steric effect of bound detergent molecules, hinders the formation of a transition state involving the sulfhydryl group, a heavy metal ion, and the ferricyanide ion.
The metabolism of α-2′ -deoxythioguanosine in murine tumor cells
Authors: LePage G. A.
Published: December 2009

Preparations of α-2′-deoxythioguanosine (α-TGdR) completely free of β-2′-deoxythioguanosine (β-TGdR) were made and labeled with radiosulfur. A purified preparation of nucleoside phosphorylase obtained from human blood cells was found to be active on the β-anomer but completely inactive on the α-anomer. This property of the enzyme was used to characterize metabolites of α-TGdR. α-TGdR and β-TGdR were both found to be converted to the corresponding mono-, di-, and tri-phosphates and incorporated into the nucleic acids of Mecca lymphosarcoma cells in vivo. α-TGdR appeared predominantly in the terminal nucleoside positions of RNA and DNA. β-TGdR appeared predominantly in the nucleotide chain. Both Mecca lymphosarcoma and Ehrlich carcinoma cells formed significant quantities of analog nucleotides at all three levels of phosphorylation, probably exceeding the levels of guanine nucleotides in the cells for an appreciable time. The findings further support a correlation reported earlier between the incorporation of 6-thioguanine into DNA and the inhibition of cell growth.
The effect of Metopirone (SU-4885) on the metabolism of progesterone by the perfused previable human fetus
Authors: Shimao Shuhei , Wiqvist Neils , Diczfalusy Egon , Solomon Samuel
Published: December 2009

A previable human fetus was first perfused with Metopirone (Metyrapone, SU-4885) and then with progesterone-7-3H. The following metabolites were isolated and identified in the fetal tissues and perfusate: 11-deoxycortisol from adrenal and perfusate; deoxycorticosterone sulfate from adrenal, perfusate, and residue; 6β-hydroxyprogesterone and 20α-dihydroprogesterone from perfusate; pregnanolone from perfusate, liver, lung, intestine, and residue; 3β-hydroxy-5α-pregnan-20-one from perfusate, liver, and residue; pregnanediol from perfusate, liver, lung, intestine, and residue; pregnanediol sulfate from adrenal, perfusate, liver, and intestine; and pregnanolone sulfate from adrenal, perfusate, liver, intestine, and residue. The results obtained demonstrate that SU-4885 inhibits 11β-hydroxylation in the human fetal adrenal and alters the metabolism of progesterone in the tissues of the human fetus, but it does not affect the ability to conjugate metabolites with sulfuric acid.
The interaction between phosphoryl transferase and submitochondrial particles
Authors: Beyer Robert E.
Published: December 2009

The interaction between purified phosphoryl transferase and submitochondrial particles has been studied. In the presence of submitochondrial particles the transferase is phosphorylated and the phosphorylated form of the transferase is dephosphorylated. Both of these interactions require that the particle be actively carrying out oxidation of succinate or NADH. Both antimycin A and oligomycin suppress the phosphorylation and dephosphorylation reactions. The uncoupler p-trifluoromethoxy-carbonylcyanide phenylhydrazone prevents the particle-mediated phosphorylation of the transferase but stimulates the dephosphorylation of the phosphorylated transferase to a slight extent. The concentration of bound adenine nucleotide in the particles appears to be a major determinant of the rate of phosphorylation of the transferase, and this dependence is consistent with the fact that the transfer of a phosphoryl group from the phosphorylated transferase to ADP proceeds rapidly and spontaneously. The probable role of the transferase in the mitochondrial transfer of phosphoryl groups from endogenous ATP to exogenous ADP is evaluated.
Isolation and properties of a fluoride-sensitive tributyrinase from adipose tissue
Authors: Lech John J. , Calvert Deane N.
Published: December 2009

Rat epididymal adipose tissue was found to contain at least two enzymes which are able to catalyze the hydrolysis of tributyrin. These activities were differentiated by their heat stability and sensitivity to inhibition by sodium fluoride. About 80% of the tributyrinase activity in epididymal adipose tissue appears to be identical with a Tween hydrolase which has been previously partially purified. This enzyme was further purified by gel filtration on Sephadex G-200, and its electrophoretic mobility was shown to be comparable with that of the major tributyrinase activity in crude extracts of adipose tissue. The substrate specificity of this enzyme indicates that it is probably not a true lipase (EC 3.1.1.3). The remaining tributyrinase activity was not fully investigated, but preliminary experiments indicate that it sediments with the microsomal fraction of adipose tissue extracts.
In vitro metabolism of estrone-4-14C and estrone-6,7-3H-3-sulfate by laying hen liver homogenates
Authors: Raud H. R. , Hobkirk R.
Published: December 2009

Estrone-4-14C and estrone-6,7-3H-3-sulfate were simultaneously incubated with hen liver homogenates prepared from fowl in the laying stage. Purification and identification of conjugated metabolites was made by two different methods: (a) an indirect procedure involving hydrolysis with a sulfatase preparation, followed by ether extraction, Girard separation, Celite partition chromatography, and crystallization to constant specific activity of the resulting free estrogens; (b) a direct identification of estrogen sulfates by paper chromatography in three different solvent systems, again followed by recrystallization. The unconjugated (free) incubation products were identified by the former of the two methods.Liver homogenates from the fowl were capable of catalyzing a rapid reduction of estrone to estradiol-17β and of estrone-3-sulfate to estradiol-17β-3-sulfate, the latter apparently without removal of the sulfate group. Under the conditions of the experiments, a slower dehydrogenation of estradiol-17β to estrone and of estradiol-17β-3-sulfate to estrone-3-sulfate was also indicated.
Glyoxylate aminotransferases from wheat leaves
Authors: King J. , Waygood E. R.
Published: December 2009

Chromatographic studies were made of the following aminotransferases in crude, dialyzed extracts of wheat leaves (Triticum aestivum L. var. Selkirk): alanine: glyoxylate; aspartate: glyoxylate; glycine: 2-oxoglutarate (EC2.6.1.4); serine: glyoxylate; L-aspartate: 2-oxoglutarate (EC 2.6.1.1); L-alanine: 2-oxoglutarate (EC 2.6.1.2).After partial purification, the properties of serine: glyoxylate aminotransferase were studied in greater detail. This reaction proceeded in the forward direction to no more than one-half completion but no reverse reaction could be detected. The enzyme showed optimum activity at pH 8.2, and Km values of 9.0 × 10−4 M for serine and 2.5 × 10−4 M for glyoxylate were obtained. No clear requirement for the coenzyme pyridoxal phosphate or for metal ion participation could be shown but orthophosphate activated the enzyme when the latter was isolated in either Tris buffer or distilled water. Various aspects of glycine metabolism are discussed in relation to this and other work recently reported using wheat blades.
Inactivation of biologically active N-methyl-N-nitroso compounds in aqueous solution: effect of various conditions of pH and illumination
Authors: McCalla D. R. , Reuvers Antoon , Kitai Ruth
Published: December 2009

The rates of decomposition of N-methyl-N′-nitro-N-nitrosoguanidine (NG), N-methyl-N-nitroso-p-toluenesulfonamide (MNTS), N-methyl-N-nitrosourea, and N-methyl-N-nitrosourethane in dilute aqueous solutions at pH levels ranging from 2 to 9 are tabulated. There are considerable differences in the breakdown rates of these compounds. At low pH, MNTS is destroyed several times faster than any of the other compounds, while at pH 7, MNTS is about 100 times as stable as methylnitrosourea. Rates of photochemical destruction of NG and MNTS are also given. Some of the breakdown products have been identified. These data are used to provide tentative explanations for some apparently anomalous biological results.
Maximum and minimum values for lecithin classes from various biological sources
Authors: Tattrie Neil H. , Bennett J. R. , Cyr R.
Published: December 2009

Lecithins from egg yolk, yeast, bovine lung, bovine livers, and hog livers were analyzed for the fatty acids in the α and β positions after hydrolysis of the fatty acids in the β position with phospholipase A. The maximum and minimum values for the four types of lecithins, viz. (1) disaturated, (2) α-saturated-β-unsaturated, (3) α-unsaturated-β-saturated, and (4) diunsaturated, were calculated for the above five lecithins and many more from data reported by other laboratories. Some of the results from some lecithins suggest that the fatty acids found in the α position may be randomly distributed with those found in the β position.
Amino acid sequences of some tryptic peptides from the β-chain of horse hemoglobin
Authors: Smith David B.
Published: December 2009

Evidence for the amino acid sequence of some peptides formed by the action of trypsin on the β-polypeptide chain of horse hemoglobin is presented. By analogy with the amino acid sequence of the β-chain of human hemoglobin, these peptides cover positions 1 to 82 and 117 to 146 of the horse β-chain. Twenty-one differences between the human and horse β-chain sequence are found in these regions.
Transient distributions ensuing when ultracentrifugal equilibrium is disturbed by a substantial increase in speed
Authors: Charlwood P. A.
Published: December 2009

An infinite series solution to the Mason–Weaver approximation to the Lamm equation is given for the case in which a system at equilibrium in the ultracentrifuge is suddenly rotated at a considerably higher speed. The greatest rate of change of concentration occurs initially at the meniscus, but later the rate of change becomes less than that in the center of the column where initially it is relatively small. Curves are presented from which to calculate, for a wide variety of conditions, the time at which it is most advantageous to transfer the level of observation from the center of the column to the meniscus. The actual rates of change of concentration at these levels at these times are tabulated. Hence, in experiments of this type interference fringes can be identified unequivocally from a limited number of photographs.
Lipid–protein interactions in abnormal egg yolk: a comparison of the major lipoprotein fractions from normal eggs and from the eggs of hens fed methyl sterculate
Authors: Burley R. W.
Published: December 2009

To help explain the known differences in texture and appearance between yolks of normal eggs and of eggs from hens whose diet contains cyclopropenoid compounds such as methyl sterculate, ultra-centrifuge patterns of solutions of the two sorts of yolk have been examined and physical and chemical properties of some of their macromolecular constituents have been compared.Abnormal yolk sedimented in 0.16 M sodium chloride, but it resembled normal yolk in that a major lipoprotein fraction floated in 1.0 M sodium chloride. This abnormal lipoprotein had a lower partial specific volume and flotation coefficient, and gave solutions with a higher viscosity, than the corresponding normal fraction. It had a higher protein content than normal, and its amino acid composition was slightly different, suggesting a different proportion of the constituent apoproteins. The abnormal lipoprotein contained slightly less of a new protein isolated because it remained soluble in a chloroform–methanol mixture. The amino acid composition of this protein differed from that of other yolk proteins. In particular, it contained very little histidine.In the abnormal lipoproteins, combination of protein and lipid appears to be such that strong interactions are possible between ngighboring lipoprotein particles in solution. In whole abnormal yolk, some of the livetins may interact with other yolk constituents thus contributing to the high viscosity. A higher proportion of saturated fatty acid residues in the lipids of abnormal yolk is the only factor so far correlated with the unusual interactions between lipid and protein in this yolk.
Glycerol as an inhibitor of cholesterol synthesis
Authors: Migicovsky B. B.
Published: December 2009

The supernatant from a homogenate of rat liver was incubated in a system containing 14C-acetate. The mixture was then saponified, the cholesterol isolated as the digitonide, and its radioactivity determined. When glycerol (water control) was a constituent of the incubation mixture, less radioactivity appeared in the digitonide. Under the same conditions, glycerol did not apparently inhibit the incorporation of 14C-mevalonate into liver cholesterol. When rats were given glycerol or glucose by mouth then 14C-acetate intraperitoneally, the total cholesterol radioactivity, specific radioactivity, and in most cases the serum cholesterol concentration, were all lower in those rats that had been given the glycerol.
Mechanism of detoxication of some organophosphorus compounds: the role of glutathione-dependent demethylation
Authors: Morello A. , Vardanis A. , Spencer E. Y.
Published: December 2009

The detoxication of the geometrical isomers of Bomyl® (dimethyl-1,3-dicarbomethoxy-1-propen-2-yl phosphate) and Phosdrin® (mevinphos, dimethyl-1-carbomethoxy-1-propen-2-yl phosphate) by mouse liver has been studied. Most of the degrading activity for Phosdrin isomers was found in the supernatant fraction, whereas for Bomyl isomers it was equally distributed between the microsomal and the supernatant fractions. cis-Phosdrin is degraded in a system which requires reduced glutathione, the metabolites being cis-monomethyl-1-carbomethoxy-1-propen-2-yl phosphate (cis-desmethyl-Phosdrin)and S-methylglutathione. On the other hand, tras-Phosdrin and both Bomyl isomers were degraded to dimethyl phosphate. A method for the synthesis of cis-thiono-Bomyl is also reported. The possible general role of glutathione in the degradation of organophosphorus compounds is discussed.
The influence of growth phase and ionic environment on the dissociation of Escherichia coli ribosomes by p-chloromercuribenzoate
Authors: Matheson A. T. , Wang Jerry Hsueh-Ching
Published: December 2009

The effect of p-chloromercuribenzoate (PCMB) on the structure of polysomes and ribosomes isolated from early log phase and stationary phase cells of Escherichia coli B has been studied in the presence and absence of K+. At 0° no breakdown of polysomes was observed in the presence of 0.5 mM PCMB. The 100S dimer, however, both at 0° and 25°, was readily dissociated under all conditions tested. The dissociation of 70S particles was much more sluggish and was most apparent in ribosomes isolated from early log phase cells in buffer containing K+. These results indicate that the sulfhydryl groups involved in 100S dissociation are more accessible to PCMB than those involved in the dissociation of 70S particles.
Simultaneous biosynthesis of pyocyanine, phenazine-1-carboxylic acid, and oxychlororaphine from labelled substrates by Pseudomonas aeruginosa Mac 436
Authors: Chang P. C. , Blackwood A. C.
Published: December 2009

Pyocyanine, phenazine-1-carboxylic acid, and oxychlororaphine are produced simultaneously by Pseudomonas aeruginosa Mac 436 in certain media. When 14C-labelled substrates were supplied, the labelled carbon was incorporated into each of the pigments in varying amounts and also into CO2 and cells. Incorporation of labelled carbon from glycerol-1,3-14C and glycerol-2-14C was better than from shikimic-1,6-14C acid, and much better than from glucose-1-14C, -2-14C, or -6-14C, succinic-1,4-14C or -2,3-14C acid, or acetic-1-14C or -2-14C acid. The data suggest that all three pigments are synthesized through the same route although some variations in the results are difficult to explain. The conclusion is that the shikimic acid pathway is the probable route of synthesis.
Codon assignments and fidelity of translation in a cell-free protein-synthesizing system from an extremely halophilic bacterium
Authors: Bayley S. T. , Griffiths E.
Published: December 2009

The incorporation of 14C-labelled amino acids into material insoluble in hot TCA under the direction of synthetic polyribonucleotides has been studied in a preincubated, cell-free system from Halobacterium cutirubrum. In the presence of 3.8 M KCl and 1.1 M NH4 salts, polyuridylic acid directed the incorporation of phenylalanine and also of leucine to the extent of 8% miscoding. This miscoding for leucine was reduced to 1% in the presence of 3.8 M KCl, 1.0 M NaCl, and 0.4 M NH4Cl. Poly C directed the incorporation of proline. The random heteropolyribonucleotides poly CA, poly CU, and poly UG directed the incorporation of only those amino acids expected on the basis of the established genetic code, together with methionine with poly UG. Quantitative comparison of the incorporation with the calculated frequencies of triplets in these polyribonucleotides suggests that the codon assignments investigated in H. cutirubrum could be identical with those in non-halophilic organisms.
Micellar properties of bile salts. Sodium taurodeoxycholate and sodium glycodeoxycholate
Authors: Kratohvil J. P. , DelliColli H. T.
Published: December 2009

Surface-tension, light-scattering, and refractometric measurements were made on aqueous solutions of sodium taurodeoxycholate and sodium glycodeoxycholate in the presence of varying amounts of NaCl or NaI (0–0.5 M). Critical micellar concentrations (c.m.c), molecular areas, refractive index increments, micellar molecular weights and aggregation numbers, and effective charges per micelle were obtained. The two conjugated bile salts exhibited rather similar behavior. The micellar properties of bile salts were much like those of typical anionic detergents. The c.m.c. values were of the order of several millimoles per liter in water, and decreased with increasing concentration of electrolyte. Areas per molecule were in the vicinity of 90 Å2, closely corresponding to the area occupied by the steroid nucleus lying flat at the interface. Aggregation numbers varied from 8 in water to about 50 in 0.5 M electrolyte solutions.
Action of proteolytic enzymes on wheat gluten
Authors: Yang Hung-Ju , McCalla A. G.
Published: December 2009

Papain and trypsin partially hydrolyzed wheat gluten dispersed in 10% sodium salicylate, and pepsin partially hydrolyzed gluten dispersed in aluminium lactate. Trypsin was considerably less effective than either papain or pepsin. Papain produced non-protein nitrogen most rapidly during early stages of hydrolysis but pepsin produced the largest total after 48 h. The rate of release of terminal amino nitrogen was similar for papain and pepsin, and release was not complete after 48 h. The mean size of polypeptides was larger in papain than in pepsin hydrolysates during early stages of hydrolysis but definitely smaller after 48 h. Only pepsin released appreciable amounts of free amino acid nitrogen. Leucine and phenylalanine made up over 50% of the free amino acids after 48 h but several other amino acids were found in significant quantities.
The nature of the glycosidic conjugates of estriol epimers in rabbits
Authors: Collins D. C. , Layne D. S.
Published: December 2009

After administration of estriol-6,7-3H to rabbits, 37% of the dose was recovered in the urine in 3 days. Estriol conjugates partially identified as glucuronosides were found, but there was no evidence for the conjugation of this steroid with N-acetylglucosamine. After hydrolysis of the radioactive steroid diglycosides with Ketodase, a conjugate was obtained, and identified by infrared and ultraviolet spectroscopy, optical rotation, and isotope dilution as the 17-N-acetylglucosaminide of 17-epiestriol. Indications were found by chromatography and enzyme treatment of the presence of smaller amounts of 16,17-epiestriol-N-acetylglucosaminide. The results confirm that rabbits excrete administered estriol partly as its 17α-epimers, and provide further evidence that the phenolic steroid N-acetylglucosaminyl transferase in this species is highly specific for the 17α-hydroxyl group.
Glycerol metabolism in rabbits
Authors: Himms-Hagen Jean
Published: December 2009

The endogenous rate of glycerol production in rabbits was measured by several techniques: constant infusion of 1,3-14C-glycerol or 2-3H-glycerol or unlabeled glycerol; single injection of 1,3-14C-glycerol or 2-3H-glycerol or unlabeled glycerol. The rate was 5.5–11.6 μmoles/kg per minute (9 rabbits). The mean fractional turnover rate was 0.0585 ± 0.0052. During infusion of noradrenaline together with 3H-glycerol, the fractional turnover rate was no different from that in the absence of noradrenaline. The maximum utilization rate of glycerol was 28.1 ± 1.40 μmoles/kg per minute. The glycerol space was 58.1% of body weight. The relationship of glycerol concentration to rate of glycerol utilization in the intact rabbit suggests the existence of an enzyme with a KM for glycerol of 0.33 × 10−3 M; the glycerol kinase of rabbit liver was found to have a KM for glycerol of 0.29 × 10−3 M. This enzyme could account for the disappearance of glycerol in the intact animal except that its Vmax is only 4% of that expected. Possible reasons for this are discussed. A glycerol dehydrogenase with a Vmax similar to that of the glycerol kinase also exists in rabbit liver; its KM for glycerol is so high (0.5 M) that it is unlikely to play a significant role in glycerol metabolism in the normal rabbit.
Two deoxyribonucleases from Novikoff ascites hepatoma cells
Authors: Ip Peter M. K. , Sung Shan-Ching
Published: December 2009

Two DNases have been isolated and separated from Novikoff ascites hepatoma by ammonium sulfate fractionation and have been further purified by chromatography on ion-exchange columns of DEAE types.The partially purified acid DNase is free of any measurable RNase activity, while the partially purified alkaline DNase preparation still exhibits RNase activity.The alkaline DNase requires sulfhydryl compounds for maximum activity, whereas the acid DNase does not. Both DNases require Mg2+ ions for maximum activity. EDTA strongly inhibits the alkaline DNase activity and the inhibition can be reversed by the addition of Mg2+ ions. On the other hand, EDTA activates the acid DNase either in the presence or in the absence of Mg2+.Sarkomycin inhibits the alkaline DNase but does not inhibit the acid DNase. Actinomycin D and heparin inhibit both DNase activities.The products of the alkaline DNase digestion consist of four deoxymononucleotides as well as higher oligonucleotides, all terminating in 5′-phosphate. The alkaline DNase seems to exhibit an endonucleolytic mode of attack in the early stage of hydrolysis with a subsequent exonucleolytic action. However, the possibility of contamination by an unknown exonuclease cannot be ruled out. On the other hand, the products of the acid DNase digestion consist mainly of oligonucleotides with average chain length larger than 8 units all terminating in 3′-phosphate. No mononucleotides can be detected. This suggests that the acid DNase is a typical endonuclease and possesses no detectable exonuclease activity.The acid DNase preferentially attacks linkages of the type dPupGp, whereas the preferential linkage(s) for the alkaline DNase has not been established.
The stimulation of the 2,4-dinitrophenol-activated ATPase by anions
Authors: Cereijo-Santaló Roberto
Published: December 2009

The activation of mitochondrial ATPase by 2,4-dmitrophenol in a sucrose medium was considerably increased in the presence of chloride ions. The effect of this anion was independent of the form in which it was added (monoethanolamine, diethanolamine, Tris, choline, sodium, or lithium chloride), with the exception that the potassium and rubidium salts were slightly more active.The effect of chloride ions was compared with that of other anions. It was found that the activity of each anion could be related to its strength as a base.
Glycerolipid metabolism in Ascaris lumbricoides
Authors: Jezyk Peter F.
Published: December 2009

Homogenates of ovarian tissue from the pig roundworm Ascaris lumbricoides rapidly incorporate fatty 14C-acids, fatty 14C-acyl-CoA derivatives, glucose, and glycerol into lipid, the most highly labeled fraction after prolonged incubation periods being the triglycerides (except with glucose). Data from studies on the time course of incorporation of these precursors is consistent with the operation of the phosphatidic acid – diglyceride pathway for biosynthesis of these lipids. However, formation and acylation of monoglyceride may also contribute to their synthesis. Determination of the composition and labeling pattern of the triglyceride species indicated that some species turn over more rapidly than others, perhaps reflecting different metabolic roles. In these experiments, only small amounts of the precursors were incorporated into phospholipids other than phosphatidic acid.
Regulatory interactions of dehydroepiandrosterone and its sulfate in rat testis tissue
Authors: Notation Albert D. , Ungar Frank
Published: December 2009

Evidence for the inhibitory effect of dehydroepiandrosterone (DHEA) on the in vitro cleavage of dehydroepiandrosterone sulfate (DHEA-SO4) by rat testis tissue was obtained. Whole homogenates of rat testis tissue were incubated with (1) DHEA-7α-3H with varying amounts of DHEA-SO4-NH4, (2) DHEA-7α-3H-SO4 with varying amounts of DHEA, (3) DHEA-7α-3H-SO4 with varying amounts of DHEA-4-14C, and (4) DHEA-7α-3H-SO4 with 100 μg of testosterone-4-14C. Time points of 5, 15, and 60 min were studied. Labeled DHEA was converted to steroid sulfates in amounts (5–10%) not affected by the amounts of DHEA-SO4 present. The amount (7–11%) of DHEA-7α-3H-SO4 converted to unconjugated steroids was decreased in the presence of either exogenous DHEA or testosterone. The distribution of label in the unconjugated steroids arising from DHEA-7α-3H-SO4 was similar to the distribution observed from labeled DHEA.
The proteins of rapeseed (Brassica napus L.) soluble in salt solutions
Authors: Bhatty R. S. , McKenzie S. L. , Finlayson A. J.
Published: December 2009

The salt-soluble proteins from rapeseed (Brassica napus L.), variety Nugget, have been extracted with 0.01 M sodium pyrophosphate (pH 7.0) and with 10% sodium chloride, and subsequently separated into a number of components. There are two major proteins in the pyrophosphate salt extract, one is neutral (the 12 S protein) and the other is basic (the 1.7 S protein). They constitute 30% of the nitrogen in the extract. There are nine other minor components in this extract. The 10% sodium chloride extract contains a water-insoluble protein (the 12 S protein) which constitutes 21% of the nitrogen in the extract and appears to be similar in properties to the 12 S protein in the pyrophosphate salt extract. This protein, upon sedimentation analysis in 6 M urea solution and in 0.1 M glycine–HCl buffer (pH 2.2), appeared to be an aggregate of units of smaller molecular weight.