Coenzyme b12

Coenzyme B12, also known as cobalamin, is a coenzyme that is involved in the metabolism of every cell of the human body. It is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system, and the formation of red blood cells.

Structure

Coenzyme B12 is structurally the most complex of all the vitamins. Its structure is based on a corrin ring, which, although similar to the porphyrin ring found in heme, chlorophyll, and cytochrome, has two of the pyrrole rings directly bonded. The central metal ion is cobalt.

Function

Coenzyme B12 is required by enzymes for two types of reactions: methyltransferase reactions and isomerization reactions. In humans, two coenzyme B12-dependent enzymes have been identified: methylmalonyl CoA mutase and methionine synthase.

Deficiency

Deficiency of coenzyme B12 can lead to megaloblastic anemia and neurological disorders. In severe cases, it can lead to irreversible damage to the brain and nervous system.

Sources

Dietary sources of coenzyme B12 include meat, milk products, and eggs. Vegetarians and especially vegans are at risk for B12 deficiency due to inadequate dietary intake.

See also

• Vitamin B12
• Cobalamin
• Methylmalonyl CoA mutase
• Methionine synthase