Cobalamin

Cobalamin with the upper axial ligand noted with R

Cobalamin may refer to several substances depending on the upper axial ligand of the cobalt ion. These are:

• Cyanocobalamin (R = -CN)
• Hydroxocobalamin (R = -OH)
• Methylcobalamin (R = -Me), an active form of vitamin B₁₂
• Adenosylcobalamin (R = -Ado), also an active form of vitamin B₁₂

Cobalamin is suseptable to acid. During its biosynthesis complexes are formed to protect it.