Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.8.1.4 (diaphorase)
 2,754 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asparagusate dehydrogenases I and II and lipoyl dehydrogenase have been obtained in homogeneous state from asparagus mitochondria. They are flavin enzymes with 1 mol of FAD/mol of protein. Asparagusate dehydrogenases I and II and lipoyl dehydrogenase have s20,w of 6.22 S, 6.39 S, and 5.91 S, respectively, and molecular weights of 111,000, 110,000, and 95,000 (sedimentation equilibrium) or 112,000, 112,000, and 92,000 (gel filtration). They are slightly acidic proteins with isoelectric points of 6.75, 5.75, and 6.80. Both asparagusate dehydrogenases catalyzed the reaction Asg(SH)2 + NAD+ equilibrium AsgS2 + NADH + H+ and exhibit lipoyl dehydrogenase and diaphorase activities. Lipoyl dehydrogenase is specific for lipoate and has no asparagusate dehydrogenase activity. NADP cannot replace NAD in any case. Optimum pH for substrate reduction of the three enzymes are near 5.9. Asparagusate dehydrogenases I and II have Km values of 21.5 mM and 20.0 mM for asparagusate and 3.0 mM and 3.3 mM for lipoate, respectively. Lipoyl dehydrogenase activity of asparagusate dehydrogenases is enhanced by NAD and surfactants such as lecithin and Tween 80, but asparagusate dehydrogenase activity is not enhanced. Asparagusate dehydrogenases are strongly inhibited by mercuric ion, p-chloromercuribenzoic acid, and N-ethylmaleimide. Amino acid composition of the three enzymes is presented and discussed.
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PMID:Asparagusate dehydrogenases and lipoyl dehydrogenase from asparagus mitochondria. Physical, chemical, and enzymatic properties. 18 3

1. The effects of lipoate and asparagusate on animal and plant enzymes of the TCA cycle and related metabolic pathways were studied. 2. Lipoate inhibited bovine liver glutamate dehydrogenase [EC 1.4.1.3]. The inhibition may play a role in metabolic regulation. 3. Asparagusate inhibited lipoyl dehydrogenase [EC 1.6.4.3] from asparagus and lettuce competitively with respect to lipoate. Asparagusate had practically no effects on other asparagus enzymes. 4. Asparagusate strongly inhibited lipoyl dehydrogenase, glutamate dehydrogenase, and isocitrate dehydrogenase [EC 1.1.1.42] from animal sources, in competition with the corresponding substrate. 5. Asparagusate and lipoate also inhibited yeast glutamate dehydrogenase. 6. Based upon kinetic studies, the mode of these inhibitions is discussed.
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PMID:Effects of asparagusate and lipoate on enzymes of the tricarboxylic acid cycle and related metabolic pathways. 77 25