Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.1 (aspartate aminotransferase)
 21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The electrophoretic mobility of several enzymes was studied in the embryos and early larvae of the hybrids between the loach (Misgurnus fossilis) and the aquarial cyprinids and cobitids (Acanthophthalmus). The cytosol aspartate aminotransferase is represented by one protein with the same mobility at all developmental stages both in the loach and in the hybrids. Malate dehydrogenase manifests four bands of isozymes which suffer no changes during the development. The electrophoretic profile of lactate dehydrogenase remains constant (10 isozymes) until hatching, but only 5 isozymes are found in the 5 days old larvae. Similar changes occur in the Misgurnus X Acanthophthalmus hybrids. The nonspecific esterases are represented by several proteins with different activities; their number increases after hatching. In the oocytes and adult specimens of Acanthophthalmus a characteristic and very active esterase was found which is absent in the loach. In the Misgurnus X Acanthophthalmus hybrids this esterase appears prior to the hatching and its activity later increases. Thus, the expression of the gene of one esterase begins in the end of embryogenesis.
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PMID:[Expression of genes controlling esterases during the embryonic development of hybrid fish]. 90 50

Malate dehydrogenase (EC 1.1.1.37) was immobilized on the lower groove of the dialyzer plate used for serum aspartate aminotransferase determination in the AutoAnalyzer II system. Immobilization was effected by covalently attaching malate dehydrogenase to the inner surface of the groove which was previously activated by treatment with glutaraldehyde at room temperature. The immobilized malate dehydrogenase catalyzed the reaction between oxaloacetate and NADH to form NAD in the coupled reaction originally proposed by Karmen. Results of the present method correlated well with those obtained by the Technicon SMA II system in which malate dehydrogenase is in solution (n = 99; r = 0.99; t = 0.30). The activity of immobilized malate dehydrogenase on the dialyzer groove was sufficient to measure serum aspartate aminotransferase for at least one month with continuous use. The stability of immobilized malate dehydrogenase was also dependent on the number of samples determined. The dialyzer plate is a reusable solid matrix for malate dehydrogenase immobilization. The expense of the present method is only half the cost of the method in which malate dehydrogenase is in solution.
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PMID:Use of malate dehydrogenase immobilized on the dialyzer groove of the Autoanalyzer II for serum aspartate aminotransferase determination. 311 24

Cell extracts of the fermentative Mollicutes Acholeplasma laidlawii B-PG9, Acholeplasma morum S2, Mycoplasma capricolum 14, Mycoplasma gallisepticum S6, Mycoplasma pneumoniae FH, Mycoplasma hyopneumoniae J and M. genitalium G-37, and the non-fermentative Mycoplasma hominis PG-21, Mycoplasma hominis 1620 and Mycoplasma bovigenitalium PG-11 were examined for 39 cytoplasmic enzyme activities associated with the tricarboxylic acid (TCA) cycle, transamination, anaplerotic reactions and other enzyme activities at the pyruvate locus. Malate dehydrogenase (EC 4.2.1.2) was the only TCA-cycle-associated enzyme activity detected and it was found only in the eight Mycoplasma species. Aspartate aminotransferase (EC 2.6.1.1) activity was detected in all Mollicutes tested except M. gallisepticum S6. Malate synthetase (EC 4.1.3.2) activity, in the direction of malate formation, was found in the eight Mycoplasma species, but not in any of the Acholeplasma species. Phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) was detected in the direction of oxaloacetate (OAA) formation in both Acholeplasma species, but not in any of the Mycoplasma species. Pyruvate carboxylase (EC 6.4.1.1), pyruvate kinase (EC 2.7.1.40), pyruvate dehydrogenase (EC 1.2.4.1) and lactate dehydrogenase (EC 1.1.1.27) activities were found in all ten Mollicutes tested. No activities were detected in any of the ten Mollicutes for aspartase (EC 4.3.1.1), malic enzyme (EC 1.1.1.40), PEP carboxytransphosphorylase (EC 4.1.1.38), PEP carboxykinase (EC 4.1.1.32) or pyruvate orthophosphate dikinase (EC 2.7.9.1). In these TCA-cycle-deficient Mollicutes the pyruvate-OAA locus may be a point of linkage for the carbons of glycolysis, lipid synthesis, nucleic acid synthesis and certain amino acids. CO2 fixation appears obligatory in the Acholeplasma species and either CO2 fixation or malate synthesis appears obligatory in the Mycoplasma species.
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PMID:Presence of anaplerotic reactions and transamination, and the absence of the tricarboxylic acid cycle in mollicutes. 314 76

The effect of increasing bilirubin concentrations upon the catalytic activity of a series of dehydrogenases and aminotransferases was examined. The particular enzymes were chosen to examine the effect of bilirubin upon the activity of enzymes responsible for the indirect transfer of reducing equivalents across the inner mitochondrial membrane. Malate dehydrogenase was inhibited at very low concentrations of bilirubin and showed competitive inhibition with respect to coenzyme of 2 microM, while the cytosolic form of this enzyme exhibited a 15 microM inhibition constant. Cytosolic glycerol-3-phosphate dehydrogenase was not appreciably inhibited by bilirubin. Both the mitochondrial and cytosolic forms of aspartate aminotransferase showed moderate competitive bilirubin inhibition with respect to substrates with a Ki of 30 microM with respect to 2-oxoglutarate and a Ki of 80 microM with respect to aspartate. Preincubation studies indicated that inhibition was reversible for all enzymes examined. These results are interpreted in terms of the inhibition of the malate-aspartate shuttle by relatively low concentrations of bilirubin.
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PMID:Bilirubin inhibition of enzymes involved in the mitochondrial malate-aspartate shuttle. 360 43

Malate dehydrogenase (EC 1.1.1.37) and aspartate aminotransferase (EC 2.6.1.1) are present in porcine blood platelets in both mitochondria and the cytosol. The latter enzyme is inhibited in a typical way by aminooxycompounds and cycloserine. Blocking of aminotransferase or inhibition of the mitochondrial dicarboxylate carrier by butylmalonate stimulates lactate production by intact platelets and inhibits their aggregation induced by ADP or collagen. These results indicate that the reoxidation of cytosolic NADH via the malate-aspartate shuttle is important for covering the energy demand of platelets necessary for their stimulation.
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PMID:Importance of the malate-aspartate shuttle for the reoxidation of glycolytically produced NADH and for cell aggregation in porcine blood platelets. 368 99

Regionally selective and time-dependent variations were observed in the activity of brain aspartate aminotransferase at early phases of diabetes. Malate dehydrogenase activity showed an opposite pattern of changes in soluble and particulate fractions of cerebral hemispheres and brain stem, with cerebellum showing consistent increase in the activity. The activity of both the enzymes increased significantly in liver, in contrast to heart where malate dehydrogenase activity decreased in particulate fraction. Insulin treatment to diabetic animals restored the enzymes to near control levels at early stages of diabetes, except in liver. The results indicate that malate-aspartate shuttle is probably stimulated under diabetic conditions to enable glycolysis to continue and ATP levels to be restored partially, particularly in cerebellum and liver.
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PMID:Malate-aspartate shuttle enzymes in rat brain regions, liver and heart during alloxan diabetes and insulin replacement. 391 Apr 26

Indian River male broiler chickens growing from 7 to 28 d of age were fed on diets containing 120, 210 and 300 g crude protein/kg diet and 0, 1.67 or 16.7 g added tryptophan (TRP)/kg diet. The hypothesis tested was that crude protein levels and TRP would affect both growth and neurotransmitter metabolism. Heart, brain and pancreatic neurotransmitter (noradrenaline (NA), dopamine (DA), serotonin (5-HT) and 5-hydroxy-indole-3-acetic acid (5-HIAA)) concentrations were determined by HPLC separation and electrochemical detection. Malate dehydrogenase (2-oxoglutarate decarboxylating) (NADP+) (MDH(NADP+); EC 1.1.1.40), isocitrate dehydrogenase (NADP+) (ICD(NADP+); EC 1.1.1.42) and aspartate aminotransferase (AAT; EC 2.6.1.1) activities were also measured. Supplemental TRP decreased growth and feed intake. Increasing dietary crude protein decreased MDH(NADP+), but increased (ICD(NADP+) and AAT activities. Additional dietary TRP decreased MDH(NADP+) activity, but had no effect on other enzyme activities. Cardiac NA concentrations were directly related to dietary crude protein levels while pancreatic levels were inversely related. An increase in dietary crude protein decreased both brain NA and DA. Supplemental dietary TRP increased both 5-HIAA and 5-HT. Changes in feed intake caused by different levels of both dietary crude protein and TRP are accompanied by altered levels of neurotransmitters. The present study indicates that much larger amounts of TRP are required to make simultaneous changes in feed intake and neurotransmitters.
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PMID:Crude protein and supplemental dietary tryptophan effects on growth and tissue neurotransmitter levels in the broiler chicken. 877 19

We demonstrate a facile blue native polyacrylamide gel electrophoresis (BN-PAGE) technique to detect two malate-generating enzymes, namely fumarase (FUM), malate synthase (MS) and four oxaloacetate-forming enzymes, namely pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), citrate lyase (CL) and aspartate aminotransferase (AST). Malate dehydrogenase (MDH) was utilized as a coupling enzyme to detect either malate or oxaloacetate in the presence of their respective substrates and cofactors. The latter four oxaloacetate-forming enzymes were identified by 2,6-dichloroindophenol (DCIP) and p-iodonitrotetrazolium (INT) while the former two malate-producing enzymes were visualized by INT and phenazine methosulfate (PMS) in the reaction mixtures, respectively. The band formed at the site of enzymatic activity was easily quantified, while Coomassie staining provided information on the protein concentration. Hence, the expression and the activity of these enzymes can be readily evaluated. A two-dimensional (2D) BN-PAGE or SDS-PAGE enabled the rapid purification of the enzyme of interest. This technique also provides a quick and inexpensive means of quantifying these enzymatic activities in normal and stressed biological systems.
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PMID:Blue native polyacrylamide gel electrophoresis and the monitoring of malate- and oxaloacetate-producing enzymes. 1615 36

Heparin and quercetin induce capacitation in spermatozoa through membrane receptor binding and inhibition of Ca-ATPase of the plasma membrane, respectively. Although capacitation is energy intensive, ammonia from amino acid metabolism can inhibit respiration and Krebs cycle activity. The objective was to determine activities of key enzymes in bull spermatozoa that contribute to the redox state and supply energy for capacitation. Malate dehydrogenase (MDH-NAD(+)), alanine and aspartate aminotransferases (ALT, AST), and lactate dehydrogenase-X (LDH-X) were measured spectrophotometrically (340 nm); mean (+/-S.D.) activities in control spermatozoa were 7.65+/-1.67, 0.45+/-0.05 and 0.74+/-0.14x10(-2)U/10(8) spermatozoa for MDH-NAD(+), ALT and AST, respectively, and were 2.83+/-0.66U/10(8) spermatozoa for LDH-X. Heparin decreased (P<0.05) activities of MDH-NAD(+), ALT, AST and LDH-X (78, 53, 66 and 66% of control levels, respectively); we inferred that amino acid catabolism was decreased. Quercetin decreased (P<0.05) activities of MDH-NAD(+) and ALT (60 and 49% of control levels), but activities of AST and LDH-X were not significantly different from controls; apparently maintenance of LDH-X activity supplied pyruvate for cellular metabolism. The proportion of capacitated spermatozoa in controls (8.5+/-1.73%) was substantially increased (P<0.05) by treatment with either heparin (36.2+/-4.5%) or quercetin (32.8+/-4.7%), there was no significant difference among groups for acrosomal integrity and sperm viability. In conclusion, heparin- or quercetin-induced capacitation affected different metabolic pathways that modulated the redox state and oxidative metabolism in cryopreserved bovine spermatozoa.
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PMID:Heparin and quercitin generate differential metabolic pathways that involve aminotransferases and LDH-X dehydrogenase in cryopreserved bovine spermatozoa. 1708 43

Malate dehydrogenase catalyzes rapid interconversion between dilute metabolites oxaloacetate and malate. Both oxaloacetate and malate are below the detection threshold of in vivo MRS. Oxaloacetate is also in rapid exchange with aspartate catalyzed by aspartate aminotransferase, the latter metabolite is observable in vivo using (13)C MRS. We hypothesized that the rapid turnover of oxaloacetate can effectively relay perturbation of magnetization between malate and aspartate. Here, we report indirect observation of the malate dehydrogenase reaction by saturating malate C2 resonance at 71.2 ppm and detecting a reduced aspartate C2 signal at 53.2 ppm due to relayed magnetization transfer via oxaloacetate C2 at 201.3 ppm. Using this strategy the rate of the cerebral malate dehydrogenase reaction was determined to be 9+/-2 micromol/g wet weight/min (means+/-SD, n=5) at 11.7 Tesla in anesthetized adult rats infused with [1,6-(13)C(2)]glucose.
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PMID:Relayed (13)C magnetization transfer: detection of malate dehydrogenase reaction in vivo. 1712 47


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