The non-equivalence of binding sites of coenzyme quinone and rotenone in mitochondrial NADH-CoQ reductase

Ahmed, Ishak ; Krishnamoorthy, G. (1992) The non-equivalence of binding sites of coenzyme quinone and rotenone in mitochondrial NADH-CoQ reductase FEBS Letters, 300 (3). pp. 275-278. ISSN 0014-5793

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/001457...

Related URL: http://dx.doi.org/10.1016/0014-5793(92)80862-B

Abstract

The fluorescent probe erythrosine 5'-iodoacetamide (ER) binds to mitochondrial NADH-CoQ reductase (Complex-I) accompanied by an enhancement of the fluorescence intensity. The binding of the CoQ analogue, 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone (DB), decreased the fluorescence intensity of the ER:Complex-I system. The 'site 1' inhibitor rotenone did not decrease the fluorescence intensity showing the non-identical nature of the binding sites of DB and rotenone. Also, the reduced form of DB did not decrease the fluorescence intensity. The decrease of the fluorescence intensity by DB was shown to be due to the removal of bound ER by DB. The rapid kinetics of ER binding was studied by temperature-jump relaxation. While DB caused complete elimination of the relaxation process in the ER:Complex-I system, rotenone caused only a decrease in the relaxation rate, suggesting conformational change. The relaxation rate showed a pH dependence with a maximum around pH 7.5.

Item Type:Article
Source:Copyright of this article belongs to Federation of European Biochemical Societies.
Keywords:NADH-CoQ Reductase; Erythrosine-5'-iodoacetamide; Fluorescence Probe; Temperature Jump; Rotenone
ID Code:17996
Deposited On:17 Nov 2010 13:22
Last Modified:17 May 2016 02:44

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