Vibrational spectroscopy of flavoproteins.

The flavin cofactor performs many functions in the cell based on the ability of the isoalloxazine ring to undergo one- or two-electron reduction and form covalent adducts with reactants such as amino acids. In addition, the strong visible absorption of the cofactor is also the basis for flavin-dependent photoreceptors. Vibrational spectroscopy is uniquely suited to studying the mechanism of flavoproteins since the frequency of the vibrational modes is very sensitive to the electronic structure and environment of the isoalloxazine ring. This chapter describes the mechanistic information that can be gained using vibrational spectroscopy as well experimental challenges and approaches that are used to obtain and interpret the complex data contained in a vibrational spectrum.