ABSTRACT
More than 100 years ago a fluorescent compound was isolated first from whey, and later from different biological materials. When it became clear that the iso-lated yellow pigments, named lactochrome, ovoflavin, or lactoflavin, had a com-mon structure, the new compound was named riboflavin (vitamin B2) (for histori-cal review see 2). In the years between 1933 and 1935 the structure and the main chemical reactions of riboflavin were studied and the chemical synthesis was performed. Soon afterward, the coenzyme forms, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), were isolated in pure form, and the struc-tures were determined. In the last 50 years many flavoproteins were isolated and their physicochemical properties were studied. Succinate dehydrogenase was the first enzyme found with the prosthetic group (FAD) covalently bound to the pro-tein. About 20 flavoproteins are now known to contain covalently bound coen-zyme (mainly via carbon atom 8α) (3). In mammalian tissue, the number of covalently bound flavoproteins appears to be limited.
