Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human plasma glutathione peroxidase (GPx) was purified to homogeneity by ammonium sulfate fractionation, gel filtration on Sephadex G-150, chromatography on DEAE Sephacel, chromatofocusing with polybuffer, and gel filtration with Sephadex G-75. This isolation resulted in about 5,400-fold purification of the enzyme with a 32% yield in enzyme activity. The final preparation had a specific activity of about 28 units (mmoles NADPH oxidized) per milligram of protein. Determination of selenium on the purified enzyme revealed a content of 3.8 g atoms per mole GPx. Gel electrophoresis using SDS with standard proteins revealed a molecular weight of about 23,000 for the subunits, which would indicate a molecular weight of about 92,000 for the native enzyme. Amino acid analyses of the purified GPx indicated aspartate, glutamate, proline, glycine, alanine, and leucine as the predominant amino acids and cysteine, methionine, tryptophan, and histidine as the minor amino acids.
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PMID:Properties of glutathione peroxidase isolated from human plasma. 366 26

1. The release of gamma-aminobutyric acid (GABA) from the surface of the posterior lateral gyrus of the cerebral cortex was measured by a sensitive enzymic fluorimetric assay procedure. Experiments were performed with anaesthetized cats during resting conditions and during cortical inhibition produced by electrical stimulation of the brain surface or of the lateral geniculate nucleus (l.g.n.).2. The average resting release of endogenous GABA was 0.20 n-mole/ 7 min.cm(2) cortex; this was increased during stimulation of both the cortical surface (2.9 times resting release during monopolar stimulation and 7.4 times resting release during bipolar stimulation) and the l.g.n. (5.7 times resting release).3. Removal of calcium ions from the collection fluid did not affect the resting release of endogenous GABA but prevented the increase in GABA release normally evoked by stimulation of the cortical surface.4. The stimulus parameters used to increase the release of GABA also inhibited the glutamate-induced firing of single cells in the visual cortex and this inhibition was abolished in the absence of calcium ions.5. In three experiments the total amino acid content of cortical samples was examined using an amino acid analyser. With the exception of GABA, there were no significant differences between the rates of release of any other detected amino acids during periods with and without electrical stimulation of the cortex.6. It is suggested that since the release of GABA observed during inhibitory stimulation of the cortex is calcium-dependent and specific, it may originate from inhibitory nerve terminals in the cortex. The present findings support the view that GABA is a central inhibitory neurotransmitter.
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PMID:The release of gamma-aminobutyric acid during inhibition in the cat visual cortex. 432 9

Norton, J. E. (University of Oklahoma School of Medicine, Oklahoma City), and J. R. Sokatch. Oxidation of d- and l-valine by enzymes of Pseudomonas aeruginosa. J. Bacteriol. 92:116-120. 1966.-Cell-free extracts prepared from Pseudomonas aeruginosa grown on dl-valine catalyzed the consumption of oxygen with several d-amino acids, but not with the corresponding l-amino acids. The product of d-valine oxidation was identified as 2-oxoisovalerate by the preparation and characterization of 2-oxoisovalerate 2,4-dinitrophenylhydrazone. The enzyme catalyzing d-amino acid oxidation was present in extracts of cells grown on valine, but not on glucose, had a pH optimum of approximately 9.0, consumed 1 atom of oxygen per mole of keto acid produced, and was not stimulated by any of the usual electron transport cofactors. It was not possible to demonstrate either the direct oxidation of l-valine or the conversion of l- to d-valine by these enzyme preparations. However, a possible route of l-valine metabolism by transamination with 2-oxoglutarate with regeneration of the amino group acceptor by glutamate oxidation was established by identification of the transaminase and l-glutamate dehydrogenase in these enzyme preparations.
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PMID:Oxidation of D- and L-valine by enzymes of Pseudomonas aeruginosa. 495 29

1. The cyst wall of Colpoda steinii has been isolated and its chemical nature examined. It had a nitrogen content 13.9+/-0.2% (s.d.) and an ash 8.6+/-1.6% (s.d.). After lipid and hot-acid extraction there was a variable residual phosphorus of 0.19-0.64%. The protein nature, indicated by infrared and ultraviolet absorption, was confirmed when 100mug. of hydrolysed wall gave a ninhydrin colour equivalent to that given by 0.88-1.01mumoles of glycine. Hexosamine, hexose, pentose, lipid and dipicolinic acid were absent. 2. Paper chromatography of hydrolysates, besides showing the presence of the usual protein amino acids and three unidentified ninhydrin-reacting spots, indicated the presence of large amounts of glutamic acid. Estimated by chromatography, the amount present was 52.9+/-0.6 (s.d.) g./100g. of ash-free wall; manometric estimation of l-glutamic acid with l-glutamate 1-carboxy-lyase gave 46.5+/-0.9 (s.d.) g./100g. 3. Free carboxyl groups were estimated by titration as 0.159+/-0.011 (s.d.) mole/100g. and those present as amide as 0.154+/-0.004 (s.d.) mole/100g., and the total was compared with the dicarboxylic acid content 0.360+/-0.010 (s.d.) mole/100g. 4. After treatment with 98% formic acid 25-30% of the wall material could be extracted by 0.05m-sodium carbonate solution (extract 1); after treatment of the residue with performic acid a further 62-63% based on the original weight could be extracted by 0.05m-sodium carbonate (extract 2). 5. The average values found for the glutamic acid contents were 21.7g./100g. for extract 1 and 58.0g./100g. for extract 2. The cysteic acid content of whole oxidized wall was about 5.8g./100g. and of extract 2 also about 5.8g./100g. The glutamic acid and cysteic acid contents of the final residue were also investigated. 6. The significance of these extraction experiments in relation to the wall structure is discussed.
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PMID:The cyst wall of Colpoda steinii. A substance rich in glutamic acid residues. 495 13

1. The accumulation of [(14)C]glycine by slices of mammalian spinal cord has been measured.2. When slices of rat cord were incubated at 37 degrees C in a medium containing [(14)C]glycine, tissue:medium ratios of about 30:1 were attained after a 40 min incubation.3. After incubations at 37 degrees C for 40 min, almost all (98%) the radioactivity in the tissue was present as unchanged [(14)C]glycine.4. The process responsible for [(14)C]glycine uptake showed many of the properties of an active transport system: it was temperature sensitive, required the presence of sodium ions in the external medium, was inhibited by dinitrophenol and ouabain and showed saturation kinetics.5. The estimated K(m) value of glycine was 3.1 x 10(-5)M, and V(max) was 0.48 mu-mole/min.g cord.6. The uptake of [(14)C]glycine was not affected by the presence of large molar excesses of L-histidine, L-proline, L-aspartate, L-glutamate, L-valine or GABA, but was inhibited in the presence of L-alanine and L-leucine.7. The uptake of [(14)C]glycine was not reduced by strychnine, but a significant reduction in uptake was produced by p-hydroxymercuribenzoate.8. The uptake of [(14)C]glycine by the grey matter of rabbit spinal cord was 2 to 6 times greater than the uptake by slices of white matter incubated under the same conditions.9. Rat cerebral cortex, cerebellar cortex and medulla also accumulated [(14)C]glycine, and the uptake by the tissue slices in vitro appeared to parallel the concentration of glycine in these areas in vivo.10. It is suggested that the glycine uptake system may represent a possible mechanism for the inactivation of glycine at inhibitory synapses in the spinal cord.
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PMID:The uptake of [14C]glycine by slices of mammalian spinal cord. 557 42

1. A study of the mode and mechanism of Cu(2+)-induced mitochondrial swelling was carried out. 2. Mitochondrial swelling curves (E(520) turbidity changes) were obtained as a function of [Cu(2+)], pH, temperature and mitochondrial protein concentration. ED(50) was approx. 70mmumoles of Cu(2+). Calculation of the activation energy from the Arrhenius equation gave a value of 22900cal./mole per degree with Q(10) 4.02. 3. No lipid peroxides were formed during swelling. 4. Changes in oxygen consumption (Clark-type electrode) were dependent on the substrate used, but revealed no increased uptake in presence of Cu(2+). 5. Cu(2+)-induced swelling was inhibited by EDTA, 8-hydroxyquinoline, cyanide, citrate, bovine serum albumin, ATP, glutamate, GSH, dithiothreitol and sucrose. Azide, Amytal, antimycin A and oligomycin had no significant effect. Potentiation of swelling was seen with ascorbate, 2,4-dinitrophenol and succinate. 6. The occurrence of different types of mitochondrial swelling and the suggestion that Cu(2+)-induced swelling is mediated through a stoicheiometric interaction with a thiol-containing membrane receptor are discussed.
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PMID:Studies of copper ion-induced mitochondrial swelling in vitro. 566 92

1. The average rate constant for loss of (45)Ca from an unpoisoned squid axon was 1.8 x 10(-3) min(-1), corresponding to an efflux of 0.2 p-mole/cm(2) sec.2. The Ca efflux from unpoisoned axons was reduced if external calcium was replaced with magnesium, or external sodium with lithium, choline or dextrose. Replacing both sodium and calcium reduced the efflux to about 40%.3. Cyanide caused little immediate change in Ca efflux but after 1(1/2)-2(1/2) hr the efflux increased to 5-15 times its normal value. The effect was rapidly reversed when cyanide was removed.4. The large Ca efflux into cyanide was reduced by a factor of three when external calcium was replaced with magnesium and by a further factor of about six when external sodium was replaced with lithium.5. The Ca efflux from both poisoned and unpoisoned axons had a Q(10) of 2-3, was not affected by ouabain and was greatly reduced by injecting ethyleneglycol bis (aminoethylether)-N,N'-tetra-acetic acid (EGTA).6. After injecting (45)Ca along the axis, the efflux of calcium reached its maximum much more rapidly in a cyanide-treated axon than in an unpoisoned axon.7. Pre-treatment with cyanide greatly increased the rate at which calcium was lost from axoplasm extruded into flattened dialysis bags. A similar effect was observed when cyanide was applied after extrusion.8. Replacing external sodium glutamate with potassium glutamate greatly reduced the loss of (45)Ca from intact axons poisoned with cyanide but had little effect on the loss from extruded axoplasm.9. The rate constant for loss of the Ca EGTA complex was about 3 x 10(-5) min(-1) for intact axons and 2 x 10(-2) min(-1) for extruded axoplasm.10. A possible explanation of the cyanide effect is that, after poisoning, calcium ions are released from a store and can then exchange at a higher rate with external sodium or calcium.11. The experiments suggest that part of the calcium efflux may be coupled to sodium entry.12. Theoretical equations for ;diffusion and chemical reaction in a cylinder' are described in the Appendix.
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PMID:The effect of cyanide on the efflux of calcium from squid axons. 576 8

The mechanism of ammonia assimilation in Methanosarcina barkeri and Methanobacterium thermoautotrophicum was documented by analysis of enzyme activities, 13NH3 incorporation studies, and comparison of growth and enzyme activity levels in continuous culture. Glutamate accounted for 65 and 52% of the total amino acids in the soluble pools of M. barkeri and M. thermoautotrophicum. Both organisms contained significant activities of glutamine synthetase, glutamate synthase, glutamate oxaloacetate transaminase, and glutamate pyruvate transaminase. Hydrogen-reduced deazaflavin-factor 420 or flavin mononucleotide but not NAD, NADP, or ferredoxin was used as the electron donor for glutamate synthase in M. barkeri. Glutamate dehydrogenase activity was not detected in either organism, but alanine dehydrogenase activity was present in M. thermoautotrophicum. The in vivo activity of the glutamine synthetase was verified in M. thermoautotrophicum by analysis of 13NH3 incorporation into glutamine, glutamate, and alanine. Alanine dehydrogenase and glutamine synthetase activity varied in response to [NH4+] when M. thermoautotrophicum was cultured in a chemostat with cysteine as the sulfur source. Alanine dehydrogenase activity and growth yield (grams of cells/mole of methane) were highest when the organism was cultured with excess ammonia, whereas growth yield was lower and glutamine synthetase was maximal when ammonia was limiting.
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PMID:Ammonia assimilation and synthesis of alanine, aspartate, and glutamate in Methanosarcina barkeri and Methanobacterium thermoautotrophicum. 612 78

The kinetic properties of glutamine synthetase (EC 6.3.1.2) isolated from pea chloroplasts and purified according to the previously developed procedure have been investigated. The pH optimum for the enzymatic reaction in the presence of Mg2+ and Mn2+ are 7.5-7.6 and 5.5, respectively. The corresponding values of the activation energy per enzyme monomer (Mr = 60 000) are equal to 2900 and 1190 cal/mole. With Mg2+ the values of Km(app.) for NH4+, NH2OH, L-glutamate (+NH4+), L-glutamate (+NH2OH), ATP(+NH4+ and NH2OH) and Mg-ATP (+NH4+ and NH2OH) are 0.64, 17.5, 5.6, 7.0, 1.3 and 0.74 mM, respectively.
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PMID:[Kinetic characteristics of glutamine synthetase from the chloroplasts of pea leaves]. 613 4

The solution spinning of a random copolypeptide of gamma-benzyl-L-glutamate polymerized with L-alanine at a mole ratio of 1 to 4 has been examined. Good fibers were obtained by using dichloroacetic acid and water as solvent and coagulation reagent respectively. The mechanical properties of the fibers are comparable with those of natural fibers.
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PMID:Spinning of a random copolypeptide composed of gamma-benzyl-L-glutamate and L-alanine. 615 20


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