Cobalamines, the coenzymatically functional forms of vitamin B12, contain cobalt as well as a corrin ring system. Corrines contain one ring member less than porphyrin systems and can coordinate Co2+ better.

Schematic depiction of the corrin ring system

3D-depiction of the uncoordinated corrin ring system


Co-Corrin Complex in the center
of vitamin B12

Details of Cobalamines
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