Riboflavin is a component of the Na(+)-pumping NADH–quinone oxidoreductase from Vibrio cholerae

Flavins are cofactors in many electron-transfer enzymes. Typically, two types of flavins perform this role: 5′-phosphoriboflavin (FMN) and flavin-adenine dinucleotide (FAD). Both of these are riboflavin derivatives, but riboflavin itself has never been reported to be an enzyme-bound component. We now report that tightly bound riboflavin is a component of the NADH-driven sodium pump from Vibrio cholerae.