Substrate Channeling of NADH and Binding of Dehydrogenases to Complex I

• Published in: The Journal of biological chemistry Vol. 264; no. 28; pp. 16483 - 16488
• Main Authors: Fukushima, T, Decker, R V, Anderson, W M, Spivey, H O
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05.10.1989; American Society for Biochemistry and Molecular Biology
• Subjects: 3-Hydroxyacyl CoA Dehydrogenases - metabolism; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Cattle; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; heart; Isoenzymes - metabolism; Ketoglutarate Dehydrogenase Complex - metabolism; Ketone Oxidoreductases - metabolism; Kinetics; Malate Dehydrogenase - metabolism; Mitochondria, Heart - enzymology; Myocardium - enzymology; NAD - metabolism; NAD(P)H Dehydrogenase (Quinone); NADH; Oxidation-Reduction; Oxidoreductases; Protein Binding; Quinone Reductases - metabolism; Substrate Specificity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)84731-2

The binding of porcine heart mitochondrial malate dehydrogenase and β-hydroxyacyl-CoA dehydrogenase to bovine heart NADH:ubiquinone oxidoreductase (complex I), but not that of bovine heart α-ketoglutarate dehydrogenase complex, is virtually abolished by 0.1 mM NADH. The malate dehydrogenase and β-hydroxyacyl-CoA enzymes compete in part for the same binding site(s) on complex I as do the malate dehydrogenase and α-ketoglutarate dehydrogenase complex enzymes. Associations between mitochondrial malate dehydrogenase and bovine serum albumin were observed. Subtle convection artifacts in short-time centrifugation tests of enzyme association with the Beckman Airfuge® are described. Substrate channeling of NADH from both the mitochondrial and cytoplasmic malate dehydrogenase isozymes to complex I and reduction of ubiquinone-1 were shown to occur in vitro by transient enzyme-enzyme complex formation. Excess apoenzyme causes little inhibition of the substrate channeling reaction with both malate dehydrogenase isozymes in spite of tighter equilibrium binding than the holoenzyme to complex I. This substrate channeling could, in principle, provide a dynamic microcompartmentation of mitochondrial NADH.