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)

Alfalfa (Medicago sativa L.) and sainfoin (Onobrychis viciifolia Scop.) are forage legumes that differ in their responses to high and low temperature stresses. Thermal limitations on the function of glutathione reductase (EC 1.6.4.2) could adversely affect the ability of the plant to cope with adverse temperatures. Our objectives were to (a) purify glutathione reductase from ;Cimarron' alfalfa and ;PI 212241' sainfoin and (b) investigate the intraspecies variation in the thermal dependency of glutathione reductase from each of three cultivars of alfalfa and two cultivars and an introduction of sainfoin. Glutathione reductase was purified 1222-and 1948-fold to a specific activity of 281 and 273 units per milligram of protein, from one species each of alfalfa and sainfoin, respectively. The relative molecular mass of the protein was approximately 140 kilodaltons with subunits of 57 and 37 kilodaltons under denaturing conditions. The activation energies were approximately 50 kilojoules per mole for both species. Over a 5 to 45 degrees C temperature gradient, large variation among species and genotypes within species was found for: (a) the minimum apparent Michaelis constant (0.6-2.1 micromoles of NADPH), (b) the temperature at which the minimum apparent Michaelis constant was observed (10-25 degrees C), and (c) the thermal kinetic windows (6-19 degrees C width). Future studies will focus on relating the thermal dependence of the Michaelis constant of the glutathione reductases and plant growth rates and forage quality of these species throughout the growing season.
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PMID:Purification and thermal dependence of glutathione reductase from two forage legume species. 1666 83

Glutathione reductase (GR, NADPH: oxidized glutathione oxidoreductase, EC 1.6.4.2) catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) using NADPH as reducing cofactor. The aim of the present work was to purify and characterize GR from bovine liver. GR was purified using 2', 5' ADP-Sepharose 4B and DEAE-Sepharose Fast Flow columns. The enzyme has been purified 5456-fold and with a yield of 38.4%. The molecular and catalytic properties of bovine liver GR have been studied. Optimum temperature and pH was found to be 50 degrees C and 7, respectively. The activation energy of the reaction catalyzed by the enzyme was 9.065 kcal/mole. The molecular weight of the enzyme was found to be 55 kDa by SDS-PAGE. Kinetic characterization of bovine liver GR was also investigated, Km(NADPH) 0.063 +/- 0.008 mM and Km(GSSG) 0.154 +/- 0.015 mM were determined. It is accepted that parallel lines observed in these double reciprocal plots obeys Ping Pong mechanism and we have showed this in our steady state study. According to our results of statistical analysis, the Ping Pong mechanism is a suitable model since the loss function is less than the other mechanisms. However, competitive inhibition by a product could be accepted in sequential mechanisms but not in a Ping Pong mechanism. In this study, kinetic data are consistent with a branching reaction mechanism previously proposed for GR from other sources by other studies.
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PMID:Purification and kinetic properties of glutathione reductase from bovine liver. 1741 Apr 7


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