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

Enzymic memory is a kinetic phenomenon observable in double displacement mechanisms. The defining feature of enzymic memory is the occurrence of different rates of transfer for a common transferable group from the substituted enzymes obtained with different donor substrates. Memory behavior was previously demonstrated for both the bovine and human liver rhodaneses (EC 2.8.1.1). Steady state kinetic tests for enzymic memory have now been done with ascorbate oxidase (EC 1.10.3.3) and aspartate aminotransferase (EC 2.6.1.1). The results were positive with ascorbate oxidase, which showed an oxygen reactivity ratio of 1:20:300 for the reduced enzymes obtained with reductate, araboascorbate, and ascorbate, respectively. Results were negative for the aminotransferase tested with the alternate donors glutamate and cysteine sulfinate, with oxaloacetate as the common acceptor. The structural basis of the ascorbate oxidase results was probed by comparison of both the ultraviolet absorption and fluorescence spectra of the oxidized enzyme with those of the reduced forms obtained with ascorbate and reductate. The results are consistent with a conformational basis for the memory phenomenon.
 ...
PMID:Enzymic memory. Steady state kinetic and physical studies with ascorbate oxidase and aspartate aminotransferase. 47 84

We have developed a sensitive method for the measurement of rhodanese activity in human serum which is based on the colorimetric method for the determination of thiocyanate produced from methanethiosulfonate and cyanide as substrates. Thiocyanate gives a red complex with ferric ion in an acidic condition. The present method is about 70-fold more sensitive than the conventional method using cyanide and thiosulfate as substrates and correlates well (r = 0.997) with the conventional method in bovine liver rhodanese. Within-run precision of the method is 0.91% for 420 units/l serum and the calibration curve is linear up to 1850 units/l. The normal value for human serum, determined by the present method on 31 healthy persons, was 20.9 +/- 20.0 units/l (mean +/- 2S.D.). Rhodanese activity was clearly elevated in some serum samples which were observed at abnormal values in some biochemical diagnostic tests and showed significant positive correlations with guanase activity (r = 0.728, p less than 0.01) and glutamic-oxalacetic transaminase activity (r = 0.625, p less than 0.01).
 ...
PMID:Improved method for measurement of rhodanese activity using methanethiosulfonate as sulfur donor substrate and its application to human serum. 166 23

Changes in the serum concentrations of aspartic aminotransferase (AST), alanine aminotransferase (ALT), rhodanese and arginase were measured in dogs, sheep and cattle with hepatic necrosis induced by the oral administration of carbon tetrachloride. A new method for arginase assay was based on the determination of remaining arginine (after its conversion to urea and ornithine) by its reaction with p-nitrophenyl glyoxal (PNPG). In all species studied the serum arginase increased 6-12 h after liver damage, reached a peak value in 48 h and returned to normal thereafter. Rhodanese activity did not change in dogs but rose significantly in sheep and, to a lesser extent, in cattle. AST increased strikingly in sheep as compared with dogs and cattle and remained high for > 5 days. In dogs ALT rose sharply and remained elevated for > 10 days. No change in ALT was seen in sheep or cattle. The determination of arginase by a simple procedure such as the PNPG method, in conjunction with AST or ALT assay, may be of value in assessing the stage of liver necrosis.
 ...
PMID:Changes in arginase, aminotransferases and rhodanese in sera of domestic animals with experimentally induced liver necrosis. 804 Mar 68

The rat liver rhodanese (thiosulphate: cyanide sulfurtransferase EC 2.6.1.1) has been immobilized on polyacrylamide gels. The immobilized enzyme had a pH optimum of 7.4 and Km values of 3.25 mM and 1.12 mM for S2O3(2-) and KCN, respectively. The enzyme was competitively inhibited by NaNO2 and CH3COONa and noncompetitively by amyl-nitrite. A modulation of activity was observed in the presence of Ca2+, Zn2+, and Cu2+. The results are discussed in line with the detoxicating function of liver rhodanese.
 ...
PMID:Immobilized rhodanese: some aspects of anion inhibition kinetics and modulation by cations. 835 60

Chronic toxicity of cyanide in humans and animals has been previously described. Alpha-ketoglutarate (alpha-KG) and sodium thiosulfate (STS) are known to confer remarkable protection against acute cyanide poisoning in rodents. Their efficacy against sub-acute or chronic cyanide exposure is not known. The objective of the present study was to assess the sub-acute toxicity of potassium cyanide (KCN) in female rats following oral administration of 7.0 mg/kg (0.5 LD50) for 14 d. The effect of alpha-KG (oral; 1.0 g/kg) and/or STS (intraperitoneal, 1.0 g/kg) on cyanide toxicity was also evaluated. Various hematological and biochemical indices were determined after 7 d of treatment and additional parameters like organ-body weight index (OBI) and histology of brain, heart, lung, liver, kidney and spleen were performed after 14 and 21 d (recovery group) of cyanide exposure. Sub-acute exposure of KCN did not produce any significant change in body weight of the animals, OBI, hematology and the levels of blood urea, creatinine, aspartate aminotransferase, triiodothyronine (T3) and tetraiodothyronine (T4). The levels of temporal glutathione disulfide (GSSG) and hepatic malondialdehyde (MDA), reduced glutathione (GSH) and GSSG were unaffected. However, in KCN treated animals elevated levels of blood glucose and reduced levels of alanine aminotransferase were observed. Activities of cytochrome c oxidase in the brain and rhodanese in the liver were diminished. Reduced levels of GSH and enhanced levels of MDA in brain were observed. Increased levels of blood thiocyanate were observed in all the treatments of KCN. Additionally, KCN also produced various histological changes in the brain, heart, liver and kidney. Although, treatment of alpha-KG and STS alone significantly blunted the toxicity of KCN, concomitant use of both interventions afforded to maximum protection. This study indicates a promising role of alpha-KG and STS for the treatment of prolonged cyanide exposures.
 ...
PMID:Effect of sub-acute oral cyanide administration in rats: protective efficacy of alpha-ketoglutarate and sodium thiosulfate. 1615 52