Coenzymes

Some enzymes have the ability to act independently while other can be functional in presence of some helpers. These helpers are of different chemical nature and two of these are important. They are cofactors and coenzymes.

Coenzymes:

They are non protein molecules that participate in enzymes catalyzed reaction, often by transporting electrons in the form of hydrogen atoms from one enzyme to another. Many vitamins like niacin and riboflavin function as coenzymes or are used to make coenzymes. The main function of coenzyme is to transport energy in the form of hydrogen atoms from one enzyme to another. One of the most important coenzyme in the cell is hydrogen acceptor micotinamide adenine dinucleotide (NAD⁺), which is made from vitamin B. Since animals have lost the ability to synthesize the vitamin components of coenzymes, it should be provided along with diet to prevent vitamin deficiency. In the body vitamins are recovered in their original form and are used repeatedly. When NAD⁺ acquires hydrogen atom from an enzyme, it reduces to NADH. The electron of hydrogen atom contains energy that the NADH molecule then carries. When various foods are oxidized in the cells, the electrons are removed from the food molecules and are transferred to these coenzymes, as NAD⁺ is reduced to NADH.