Biosynthesis of vitamin B12: Concerning the identity of the two-carbon fragment eliminated during anaerobic formation of cobyrinic acid

AUTOR(ES)

Wang, Jianji

FONTE

The National Academy of Sciences of the USA

RESUMO

It has been proved that, during anaerobic biosynthesis of the corrin macrocycle, the two-carbon fragment excised from the precursor, precorrin-3, is acetaldehyde, which originates from C-20 and its attached methyl group. This apparently contradictory finding is rationalized in terms of the subsequent enzymatic oxidation of acetaldehyde to acetic acid, which was previously regarded as the volatile fragment released by the action of the biosynthetic enzymes of Propionibacterium shermanii. The observation that acetaldehyde (rather than acetic acid) is extruded during anaerobic B12 synthesis is in full accord with the structure of factor IV, a new intermediate on the pathway.

Documentos Relacionados

• Biosynthesis of vitamin B12: identity of fragment extruded during ring contraction to the corrin macrocycle.
• Biosynthesis of vitamin B12: mode of incorporation of factor III into cobyrinic acid.
• Biosynthesis of vitamin B12: Mode of incorporation of factor III into cobyrinic acid
• Biosynthesis of vitamin B12: nature of the volatile fragment generated during formation of the corrin ring system.
• Biosynthesis of vitamin B12: concerning the origin of the methine protons of the corrin nucleus.