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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)

Re-investigating the accuracy of the commonly used values for molar absorptivities (epsilon) of beta-NADH and beta-NADPH at Hg 334, Hg 365, or 340 nm, we obtained the following results: The maximum of absorbance of NADH is shifted from about 340 nm at 0 degrees C to about 338.5 nm at 38 degrees C; the corresponding maxima of NADPH are located at about 0.5-nm longer wavelengths. In addition, the absorption curves of both coenzymes broaden with increasing temperature. For these reasons, the epsilon-values of NADH and NADPH are generally different from each other, and are temperature-dependent. Only at 334 nm are they almost identical and nearly independent of temperature. Therefore this wavelength is recommended for precise measurements. The epsilon-values of these coenzymes are influenced by ionic strength and pH. To determine the absolute values of the molar absorptivities, we performed the glutamate dehydrogenase or lactate dehydrogenase assay with carefully purified 2-oxoglutaric acid or pyruvic acid in the presence of excess coenzyme. The purity of the substrates was checked through differential scanning calorimetry, moisture analysis, gas-liquid chromatography, gas chromatography in combination with mass spectrometry, and nuclear magnetic resonance spectroscopy. The epsilon-values observed under the various conditions are about 1-7% higher than those currently used.
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PMID:Molar absorptivities of beta-NADH and beta-NADPH. 0 89

Various flavins, FMN, FAD, and acriflavin, were immobilized to Sepharose using several different coupling methods. The only product stable enough to permit extended studies was acriflavin coupled to epoxy-substituted Sepharose. The nonenzymic oxidizing capacity towards NAD(P) H was investigated and a 25% specific activity, compared to that of free acriflavin, was observed. The reduced acriflavin was immediately auto-reoxidized in air and could thus be reused. It was shown that acriflavin-Sepharose preparations function as NAD(P)H oxidizing agents in a number of different dehydrogenase systems including lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), malate dehydrogenase (MDH), alanine dehydrogenase (alaDH), and glutamate dehydrogenase (GDH). The amount of expensive coenzyme necessary for high product formation of such systems was thereby markedly reduced.
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PMID:Continuous regeneration of NAD(P)+ by flavins covalently bound to sepharose. 0 69

Activities of 9 enzymes were determined biochemically in the endometrium. In Trial I (five women) 25 mg progesterone were injected i.m. on day 9 of the cycle; and endometrial biopsy taken 24 hours later was compared with endometrium from day 10 and day 21, taken in two untreated cycles from the same volunteers. Similarly, in Trial II (five women) 50 mg progesterone were injected on day 9, biopsy taken on day 11 and compared with days 11 and 21 from untreated cycles. The specific activites of lactate dehydrogenase, isocitrate dehydrogenase (ICDH), malate dehydrogenase, glutamate dehydrogenase, beta-glucuronidase, acid phosphatase (ACP) and alkaline phosphatase (AP) were significantly higher in the secretory phase. Twenty-five milligrams progesterone (after 24 hours) caused increases of some enzymes, significant only for AP. Fifty milligrams (after 48 hours) increased significantly the activity of ICDH and ACP. Biochemical changes, especially increase of ICDH, can be used for detection of the effect of progesterone on the endometrium.
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PMID:Effect of endogenous and exogenous progesterone on human endometrial enzymes. 3 Jul 6

1) A lysosomal protease, a new cathepsin that inactivates glucose-6-phosphate dehydrogenase [EC 1.1.1.49] and some other enzymes and differs from cathepsin B [EC 3.4.22.1] was purified about 2,200-fold from crude extracts of rat liver by cell-fractionation, freezing and thawing, acetone treatment, gel filtration, and DEAE Sephadex and CM-Sephadex column chromatographies. 2) The new cathepsin was markedly activated by the thiol-reagent, 2-mercaptoethanol and inhibited by monoiodoacetate. 3) The molecular weight of the new cathepsin was found by Sephadex G-75 column chromatography to be 22,000, which is smaller than that of cathepsin B. 4) The optimum pH of the enzyme for inactivation of glucose-6-phosphate dehydrogenase was pH 5.0--5.5. The enzyme was unstable in alkali and on heat treatment. 5) The rates of inactivation of glucose-6-phosphate dehydrogenase, apo-ornithine aminotransferase [EC 2.6.1.13], apo-tyrosine aminotransferase [EC 2.6.1.5], apo-cystathionase [EC 4.4.1.1], glucokinase [EC 2.7.1.2], glyceraldehyde-3-phosphate dehydrogenase [EC 1.2.1.12], and malate dehydrogenase [EC 1.1.1.37] by the new cathepsin were higher than those by cathepsin B. However aldolase [EC 4.1.2.13] was inactivated more rapidly by cathepsin B than by the new cathepsin. Lactate dehydrogenase [EC 1.1.1.27], glutamate dehydrogenase [EC 1.4.1.2] and alcohol dehydrogenase [EC 1.1.1.1] were not inactivated by either cathepsin. Unlike cathepsin B, the new cathepsin scarcely hydrolyzes N-substituted derivatives of arginine.
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PMID:Purification and properties of a new cathepsin from rat liver. 3 59

We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.
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PMID:Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer. 3 20

A histochemical evaluation of the activity of chosen oxido-reductive enzymes of the cardiac muscle connected with the citric acid cycle, glycolysis and pentose shunt in the early experimental alloxan diabetes period in white rats has been carried out. Dehydrogenases: succinate, isocitrate and glucose-6-phosphate indicated a decrease in the enzymatic activity while the lactate dehydrogenase activity did not undergo any change. An increase in the intensity of the histoenzymatic reaction only concerned glutamate dehydrogenase. The presented histoenzymatic evidence of changes in the enzymatic activities may speak for the possibility of an existence of a direct diabetes influence on the cardiac muscle metabolism.
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PMID:Some histochemical observations on the myocardial metabolism in experimental conditions. Part II. 9 52

Adaptation of Ehrlich ascites tumor cells to serial cultivation in media with progressively elevated (hypertonic) NaCl content ("high NaCl"-tolerant cells) has resulted in progressive increases of the cellular activities of NAD-dependent glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), NAD-dependent malate dehydrogenase (EC 1.1.1.37), glutamate--oxalacetate transaminase (EC 2.6.1.1), NAD (P)-dependent glutamate dehydrogenase (EC 1.4.1.3), NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42). The activities of glutamate-pyruvate transaminase (EC 2.6.1.2.) and of glycolytic enzymes as phospho-fructokinase (EC 2.7.1.11), glyceraldehydephosphate dehydrogenase (EC 1.2.1.12) and lactate dehydrogenase (EC 1.1.1.27) were only slightly and not in progressive manner (in response to the progressive increase of the environmental NaCl concentration) affected. These changes are discussed with respect to a metabolic pattern of these "high NaCl"-tolerant cells which is compatible with increased energy requirements, especially for active cation transport. It is suggested that these increased cellular enzyme activities reflect an increased transfer of reducing equivalents across mitochondrial membranes (via the "glycerophosphate cycle and the malate-aspartate shuttle") and possibly a stimulated lipid metabolism. These alterations in the level of enzyme activities must be regarded asan adaptive cellular response to the "high NaCl" environment, since readaptation to growth in regular isotonic media resulted in a reversion to the enzyme pattern characteristic of the parent cells.
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PMID:Changes in enzyme pattern of Ehrlich ascites tumor cells following serial cultivation in media with increased (hypertonic) NaCl content. 12 1

We have shown that nuclei isolated by two methods contain grossly different amounts of cyclic AMP-dependent histone kinase activity. Repeated washing of the isolated nuclei with a low ionic strength buffer removed the majority of the cyclic AMP-dependent histone kinase and cyclic AMP binding activity. Nuclear cyclic AMP-dependent histone kinase activity accounted for only 0.42% of the total cytoplasmic enzyme activity. Similarly, the lactate dehydrogenase activity associated with liver nuclei represented only 0.07% of the total cytoplasmic activity. The isolated liver nuclei contained only 0.27% of the total homogenate glutamate dehydrogenase activity and 1.7%of the total homogenate glucose-6-phosphatase activity. The cyclic AMP-dependent histone kinase behaves as a cytoplasmic rather than a nuclear enzyme. We have also shown that using crude extracts, one can achieve separation of the two nuclear casein kinases, NI and NII, on sucrose density gradients in the presence of 0.5M NaCl. Nuclear casein kinases NI and NII had sedimentation coefficients of 3.0 and 593 S, respectively, in the presence of 0.5 M NaCl. Under conditions of low ionic strength, all of the casein kinase activity in the crude nuclear extract sedimented as one peak with a seminentation coefficient of 7.3 S. The aggregation-disaggregation which occurred in the crude extract was reversible and was mainly due to the aggregative and disaggregative properties of casein kinase NII. The two nuclear casein kinases have different affinities for chromatin. When nuclei were disrupted in a hypotonic solution and extracted with a buffercontaining 0.14 M NaCl, casein kinase NII could be completely extracted from the viscous nuclear material. Although a significant amount of casein kinase NI was extracted by the buffer containing 0.14 M NaCl, re-extraction of the nuclear material with a buffer containing 0.5 M NaCl yielded substantial amounts of casein kinase NI, and a final extraction with a buffer containing 1.0 M NaCl yielded measurable amounts of casein kinase NI. No casein kinase NII activity could be detected in the 0.5 M and 1.0M NaCl extracts.
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PMID:Rat liver nuclerar protein kinases. 16 84

A tetrazolium staining medium incorporated in a gel has been used in a histochemical study of enzymes in thin sections of heart muscle. Formazan distribution patterns given by mitochondrial enzymes were inconsistent with the location of these enzymes revealed by the extraction of whole tissue. Similar stain distributions were given by lactate dehydrogenase, glutamate oxaloacetate transaminase and glutamate dehydrogenase. The distribution given by succinate dehydrogenase was not the same as that given by cytochrome oxidase stained by a different technique. Alcohol dehydrogenase added to the tissue assumed a distribution which suggested some adsorption of the enzyme to the tissue. But experiments suggested that this enzyme was not firmly bound to muscle proteins in the manner of some glycolytic enzymes.
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PMID:Localization in cardiac muscle of some enzymes related to glutamate metabolism. 16 67

Continuous loss of bile in rats with a bile reservoir applied to the common bile duct caused an increase in specific activity of malic dehydrogenase, lactic dehydrogenase, glutamic dehydrogenase, glucose-6-phosphoric dehydrogenase, alkaline and acid phosphatase, urokinase and histidinase in the liver homogenates by the 7th day; the specific activity decreased by the 10th day. Disruption of innervation of the liver caused a sharp decrease of the ATP content and the abovementioned specifc activity in this organ. In continuous loss of bile there were revealed oscillations in the activity of the above-mentioned enzymes and sorbitol dehydrogenase in bile from the 1st to the 10th day of the experiment. Marked changes in the oscillations in the dysinnervated liver were in favour of the fact that those oscillations coursed under the control of the nervous system.
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PMID:[Enzyme activity of the bile and liver after disruption of its innervation and bile loss]. 18 5


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