Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method is described for determining the activity of deoxycytidylate deaminase in serum. The ammonia liberated from deoxycytidine monophosphate has been specifically determined by enzymatic amination of alpha-ketoglutarate using glutamate dehydrogenase. The concurrent oxidation of NADH2 at 340 nm was proportional to the ammonia liberated from deoxycytidine monophosphate. Using the technique described, a result would be available to the clinician in under 4.5 h. The "normal activity" for deoxycytidine deaminase in normal male, female and pregnancy sera has been determined.
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PMID:A rapid method for the determination of deoxycytidylate deaminase activity in pregnancy serum. 24 May 23

1. It is shown by limited tryptic digestion of beef liver glutamate dehydrogenase under native conditions that the amino terminus of the polypeptide chain is located at the surface of the molecule. End-group analysis after trypsin treatment yields aspartic acid as the new N-terminal amino acid while the C-terminal threonine remains unchanged. 2. NADH, especially in the presence of 2-oxoglutarate, protects the enzyme against tryptic degradation. In the absence of the coenzyme, glutamate dehydrogenase is rapidly inactivated. 3. The regulatory effects of ADP and GTP are only slightly altered by trypsin. A small shift of the pH dependence of the activation by ADP is observed. 4. The quaternary structure of the unimer of the enzyme is not affected by limited tryptic digestion indicating that the N-terminal part of the polypeptide chain is not located in the contact domains between the polypeptide chains. The association of the hexamer to large associated particles is reduced but not abolished. 5. It is shown by treatment of the enzyme with iodo[2(-14)C]acetic acid as well as with Ellman's reagent that the six - SH groups of the polypeptide chain are buried and not accessible to these reagents in phosphate buffer. In Tris buffer they become exposed and react in the order 89, 55, 197, 115, 270, 319. This together with the result that in Tris buffer the rat of inactivation caused by trypsin is higher than in phosphate buffer indicates that Tris buffer changes drastically the properties of the enzyme. 6. Cross-linking of the enzyme molecule with bifunctional reagents and subsequent dodecylsulfate-polyacrylamide electrophoresis shows that the six identical polypeptide chains are arranged in two groups of three. 7. The implications of these results for the tertiary and quaternary structure of beef liver glutamate dehydrogenase are discussed.
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PMID:Studies of glutamate dehydrogenase: analysis of functional areas and functional groups. 24 Jun 78

Glutamate dehydrogenase (L-glutamate:NADP+ oxidoreductase [deaminating], EC 1.4.1.4) has been purified from Escherichia coli B/r. The purity of the enzyme preparation has been established by polyacrylamide gel electrophoresis, ultracentrifugation, and gel filtration. A molecular weight of 300,000 +/- 20,000 has been calculated for the enzyme from sedimentation equilibrium measurements. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate and sedimentation equilibrium measurements in guanidine hydrochloride have revealed that glutamate dehydrogenase consists of polypeptide chains with the identical molecular weight of 50,000 +/- 5,000. The results of molecular weight determination lead us to propose that glutamate dehydrogenase is a hexamer of subunits with identical molecular weight. We also have studied the stability and kinetics of purified glutamate dehydrogenase. The enzyme remains active when heat treated or when left at room temperature for several months but is inactivated by freezing. The Michaelis constants of glutamate dehydrogenase are 1,100,640, and 40 muM for ammonia, 2-oxoglutarate, and reduced nicotinamide adenine dinucleotide phosphate, respectively.
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PMID:Glutamate dehydrogenase from Escherichia coli: purification and properties. 24 44

Two strains of Cyanidium caldarium, one able to utilize nitrate as a substrate, and the other not, were tested for the presence of enzymes of ammonia assimilation. The nitrate-assimilating strain exhibits glutamate dehydrogenase activity. By contrast, the other strain lacks glutamate dehydrogenase; it possesses high alanine dehydrogenase and L-alanine aminotransferase activities which suggest that this strain may incorporate ammonia through reductive amination of pyruvate and may form glutamate from 2-ketoglutarate by a transamination reaction with alanine. Neither strain reveals glutamate synthase activity. Both strains contain similar levels of glutamine synthetase.
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PMID:Observations on enzymes of ammonia assimilation in two different strains of Cyanidium caldarium. 24 91

The effects of 0-30% methanol (vol/vol) on the Km an Vm values for both the forward and reverse directions of the L-glutamate dehydrogenase reaction were determined at 0 degrees C. The decrease in temperature alone had very little effect on these parameters. However, in the forward reaction, 30% methanol resulted in a 14-fold decrease in the Km value for glutamate, a slight decrease in the Km value for NADP, and a thirty-fold decrease in Vm. Substrate inhibition by glutamate was observed at concentrations greater than 4 mM. In the reverse reaction, 30% methanol caused a decrease in the Km values for alpha-ketoglutarate and ammonia and a 10-fold decrease in Vm. Substrate inhibition by both alpha-ketoglutarate and NADPH was observed at concentrations of either substrate above 0.03 mM. The dependence of Km for glutamate and Vm values for the forward reaction on methanol concentration suggests that they are similarly affected by methanol, in direct contrast to results obtained for NADP. Methanol appeared to cause a general tightening of complexes, which may arise from an effect on the "activities" of species in solution. The use of methanol not only allows for the study of reaction intermediates by slowing the reaction with the cryogenic method, but may also serve as a mechanistic probe by affecting several polarity as well as Km, Vm, and K1 values.
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PMID:The effects of methanol on the glutamate dehydrogenase reaction at 0 degrees C. 26 5

Malaria-infected red cells and free parasites have limited capabilities for the biosynthesis of amino acids. Therefore, the principal amino acid sources for parasite protein synthesis are the plasma free amino acids and host cell haemoglobin. Infected cells and plasmodia incorporate exogenously supplied amino acids into protein. However, the hypothesis that amino acid utilization (from an external source) is related to availability of that amino acid in haemoglobin is without universal support: it is true for isoleucine and for Plasmodium knowlesi and P. falciparum, but not for methionine, cysteine, and other amino acids, and it does not apply to P. lophurae. More by default than by direct evidence, haemoglobin is believed to be the main amino acid reservoir available to the intraerythrocytic plasmodium. Haemoglobin, ingested via the cytostome, is held in food vacuoles where auto-oxidation takes place. As a consequence, haem is released and accumulates in the vacuole as particulate haemozoin (= malaria pigment). Current evidence favours the view that haemozoin is mainly haematin. Acid and alkaline proteases (identified in crude extracts from mammalian and avian malarias) are presumably secreted directly into the food vacuole. They then digest the denatured globin and the resulting amino acids are incorporated into parasite protein. Cell-free protein synthesizing systems have been developed using P. knowlesi and P. lophurae ribosomes. In the main these systems are typically eukaryotic.Studies of amino acid metabolism are exceedingly limited. Arginine, lysine, methionine, and proline are incorporated into protein, whereas glutamic acid is metabolized via an NADP-specific glutamic dehydrogenase. Glutamate oxidation generates NADPH and auxiliary energy (in the form of alpha-ketoglutarate). The role of red cell glutathione in the economy of the parasite remains obscure. Important goals for future research should be: quantitative assessment of the relative importance of amino acid sources for parasite protein synthesis; purification and characterization of plasmodial proteinases; and in vitro translation of parasite messenger RNA.
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PMID:Amino acid metabolism and protein synthesis in malarial parasites. 33 83

Klebsiella aerogenes utilized arginine as the sole source of carbon or nitrogen for growth. Arginine was degraded to 2-ketoglutarate and not to succinate, since a citrate synthaseless mutant grows on arginine as the only nitrogen source. When glucose was the energy source, all four nitrogen atoms of arginine were utilized. Three of them apparently did not pass through ammonia but were transferred by transamination, since a mutant unable to produce glutamate by glutamate synthase or glutamate dehydrogenase utilized three of four nitrogen atoms of arginine. Urea was not involved as intermediate, since a unreaseless mutant did not accumulate urea and grew on arginine as efficiently as the wild-type strain. Ornithine appeared to be an intermediate, because cells grown either on glucose and arginine or arginine alone could convert arginine in the presence of hydroxylamine to ornithine. This indicates that an amidinotransferase is the initiating enzyme of arginine breakdown. In addition, the cells contained a transaminase specific for ornithine. In contrast to the hydroxylamine-dependent reaction, this activity could be demonstrated in extracts. The arginine-utilizing system (aut) is apparently controlled like the enzymes responsible for the degradation of histidine (hut) through induction, catabolite repression, and activation by glutamine synthetase.
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PMID:Utilization of arginine by Klebsiella aerogenes. 34 1

These studies were designed to determine the biochemical nature of the Bacillus thuringiensis growth being dependent on glutamate during cultivation in a minimal medium. This is possible to be due to the absence of enzymes which catalyze glutamic acid synthesis by direct amination of alpha-ketoglutaric acid, glutamate dehydrogenase and glutamate synthase, and a decrease in the activity of the enzyme catalyzing amination of pyruvic acid, alanine dehydrogenase. It has been shown that the lack of glutamate can be compensated by histidine and proline; in this case, the growth efficiency of R form is greater than that of S form which is consistent with an increased rate of protein synthesis of R form.
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PMID:[Amination and biosynthesis of glutamate by R- and S-forms of Bacillus thuringiensis]. 47 Jun 35

Ammonia is known to inhibit the steady-state rate of oxidation of L-glutamate catalyzed by glutamate dehydrogenase. We reported previously [Brown, A., Colen, A. H., & Fisher, H. F. (1978) Biochemistry 17, 2031] kinetic evidence supporting the formation in the initial rapid phase of a complex which is composed of enzyme, reduced coenzyme, alpha-ketoglutarate, and ammonia. We show here that the effects of ammonia on the steady-state reaction can be correlated with transient-state kinetic effects related to the concentration of that ammonia-containing complex. These results indicate the existence of alternate reaction pathways which become important at high ammonia concentrations. These new pathways provide an additional route for the release of NADPH from the enzyme surface. The expanded mechanism shows that the noncompetitive product inhibition by ammonia can occur without the simultaneous presence of ammonia and L-glutamate on the enzyme. This mechanism also accommodates the observed substrate inhibition by L-glutamate.
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PMID:Effect of ammonia on the glutamate dehydrogenase catalyzed oxidative deamination of L-glutamate. The steady state. 51 77

Stopped-flow studies of the initial burst of NADPH production accompanying the oxidative deamination of L-glutamate by L-glutamate dehydrogenase and NADP+ were performed in the presence of alpha-ketoglutarate, a product of the reaction. Both binary enzyme-alpha-ketoglutarate and ternary enzyme--NADP+-alpha-ketoglutarate complexes are inhibitory in the burst presence of the enzyme-catalyzed reaction. Order-of-addition experiments show the binary complex to form rapidly, in the 3 ms dead time of the stopped-flow instrument. There is a distinct lag, however, in the achievement of the full ternary complex inhibitory effect unless the enzyme is preincubated with both NADP+ and alpha-ketoglutarate prior to initiation of the catalytic reaction with L-glutamate. The formation of an inhibitory enzyme--NADP+-alpha-ketoglutarate complex appears to be sufficiently slow to give a delayed kinetic response when alpha-ketoglutarate is added to the reaction system.
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PMID:Transient-state kinetics of L-glutamate dehydrogenase: mechanism of alpha-ketoglutarate inhibition in the burst phase. 56 27


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