Biosynthesis of vitamin B 6 . Incorporation of glycolaldehyde into pyridoxal

Radioactivity from [14C]glycolaldehyde enters pyridoxal phosphate specifically, and is confined to the two-carbon unit C(5)–C(5′). Glycolaldehyde enters as an intact two-carbon unit, the aldehyde carbon atom supplying C-5, and the carbinol carbon atom C-5′ of the vitamin. These observations are interpreted in terms of the early stages of the biosynthesis of vitamin B6.