Light-Induced Alkylation and Dealkylation of the Flavin Nucleus.

The spectral course of irreversible photoreduction of the flavin nucleus by arylacetates and related compounds has been investigated in detail. The resulting benzylated dihyro flavins and their reoxidation products have been characterized spectrophotometrically, among them 5-benzyl-flavosemiquinone radical and 5-benzylflavoquinonium cation. Reversible and irreversible flavin reduction corresponding to hydride-or group-transfer from substrate to flavin are discussed with respect to their scope and limitations and possible biological implications I the action mechanism of flavin dependent dehydrogenases. [ABSTRACT FROM AUTHOR]