COVALENT ATTACHMENT OF FLAVIN ADENINE-DINUCLEOTIDE (FAD) AND FLAVIN MONONUCLEOTIDE (FMN) TO ENZYMES - THE CURRENT STATE OF AFFAIRS

The first identified covalent flavoprotein, a component of mammalian s uccinate dehydrogenase, was reported 42 years ago. Since that time, mo re than 20 covalent flavoenzymes have been described, each possessing one of five modes of FAD or FMN linkage to protein. Despite the early identification of covalent flavoproteins, the mechanisms of covalent b ond formation and the roles of the covalent links are only recently be ing appreciated. The main focus of this review is, therefore, one of m echanism and function, in addition to surveying the types of linkage o bserved and the methods employed for their identification. Case studie s are presented for a variety of covalent flavoenzymes, from which gen eral findings are beginning to emerge.