Vitamin B12 contains which metal at its center?
ACobalt (only Co-containing biomolecule; in corrin ring)
BZinc
CMagnesium
DIron
Answer & Solution
Correct answer: A. Cobalt (only Co-containing biomolecule; in corrin ring)
B12 (cobalamin): central Co atom in corrin ring (similar to but smaller than porphyrin). Only Co-containing biomolecule known. Hemoglobin has Fe in porphyrin; chlorophyll has Mg. B12 essential for nucleic acid synthesis, neurological function; deficiency causes pernicious anemia.
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