Chemical Aspects of Riboflavin

HISTORICAL SKETCH The chemical nature of the water-soluble yellow green-fluorescent pigment of whey now referred to as riboflavin (synonymous with lactoflavin, vitamin G and vitamin B2, as used by many English and German investigators) commanded the attention of chemists1as early as 1879. A considerable concentration of this pigment was effected and certain of its more obvious chemical properties were clearly set forth by Bleyer and Kallmann2in 1925. No unusual significance was associated with this pigment by these early workers, who apparently regarded it only as one of the minor constituents of milk, the chemical nature of which was quite obscure. In 1932 Warburg and Christian3described a new oxidation enzyme obtained from aqueous extracts of yeast. The enzyme in water solutions was yellow and exhibited a green fluorescence. Together with a second enzyme obtained from yeast and a co-enzyme obtained from the red blood