RESEARCH
Chemists Suggest Coenzyme B12 Structure Research on structure of coenzyme form of vitamin B12 shows adenine nucleoside attached to cobalt, no cyano group HERE'S HOW THE STRUCTURES OF VITAMIN B* AND COENZYME B u SEEM TO DIFFER
The metabolic role of vitamin B 1 2 may be a lot easier to pin down now. Reason: The structure of coenzyme B 12 , metabolically active form of the vitamin, has been suggested by Dr. H. A. Barker and co-workers at the University of California, Berkeley. The California group recently isolated the coenzyme in purified, crystalline form. The coenzyme's structure is similar to the vitamin's except that it has no cyano group linked to cobalt. Instead, it has an adenine nucleoside that seems to be linked to cobalt as the cyano group is in vitamin B12', Dr. Barker finds. Crystallographic data are consistent with such a structure. Complete structure of the nucleoside isn't certain yet. It contains adenine and a sugar. But the sugar is definitely not ribose, as might be expected, Dr. Barker says. Evidently, the sugar is an aldose containing three neighboring hydroxyl groups, and is attached to adenine's N-9 position.
The vitamin has a cyano group; the coenzyme has an adenine nucleoside instead
SUGA*.
YSPTAMIfil a .
(Structure unknown, except that It's an aldose with three neighboring hydroxyls)
