Title:Reversible dissociation of flavin mononucleotide from the mammalian membrane-bound NADH: ubiquinone oxidoreductase (complex I).
Authors:Gostimskaya IS; Grivennikova VG; Cecchini G; Vinogradov AD
Publication:FEBS Lett. 2007 Dec 22;581(30):5803-6. doi: 10.1016/j.febslet.2007.11.048. Epub 2007 Nov 26.
Conditions for the reversible dissociation of flavin mononucleotide (FMN) from the membrane-bound mitochondrial NADH:ubiquinone oxidoreductase (complex I) are described. The catalytic activities of the enzyme, i.e. rotenone-insensitive NADH:hexaammineruthenium III reductase and rotenone-sensitive NADH:quinone reductase decline when bovine heart submitochondrial particles are incubated with NADH in the presence of rotenone or cyanide at alkaline pH. FMN protects and fully restores the NADH-induced inactivation whereas riboflavin and flavin adenine dinucleotide do not. The data show that the reduction of complex I significantly weakens the binding of FMN to protein thus resulting in its dissociation when the concentration of holoenzyme is comparable with K(d ( approximately 10(-8)M at pH 10.0).