Activation of succinate dehydrogenase by 2,4-dinitrophenol-a competitive inhibitor

Susheela, L and Ramasarma, T (1971) Activation of succinate dehydrogenase by 2,4-dinitrophenol-a competitive inhibitor. In: BBA - Enzymology, 242 (3). pp. 532-540.

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Abstract

1.The reported inhibition of the succinate oxidase system at high concentrations of dinitrophenol, considered to be at the primary dehydrogenase level, is now confirmed by measuring the activity of succinate dehydrogenase (succinate:(acceptor) oxidoreductase, EC 1.3.99.1) in the presence of dinitrophenol, using the dye reduction method. 2. 2. The results indicate that the inhibition of substrate-activated succinate dehydrogenase by dinitrophenol is competitive. 3. 3. Low concentrations of dinitrophenol inhibited the basal activity, while at higher concentrations the kinetics were complicated by an apparent activation. 4. 4. Preincubation of mitochondria with dinitrophenol stimulated the enzyme activity, a phenomenon shown by succinate and competitive inhibitors. This activation was very rapid at 37°, compared to that by succinate; activation by dinitrophenol was observed even at 25°, under conditions where succinate had no effect. 5. 5. Repeated washing of the activated mitochondrial samples with the sucrose homogenizing medium reduced the succinate-stimulated activity to the basal level, but only partially reversed the dinitrophenol activation. 6. 6. The relevance of this activation phenomenon to the physiological modulation of this enzyme system is discussed.

Item Type:	Journal Article
Publication:	BBA - Enzymology
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	23 Jun 2010 11:04
Last Modified:	19 Sep 2010 06:08
URI:	http://eprints.iisc.ac.in/id/eprint/28376

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