Cofactors

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.

Cofactors:

Many enzymes require certain metal ions to change non functioning active site to a functioning one. These metal ions that help enzyme in their catalytic activity are known as cofactors. Some of common cofactors are Ca²⁺, Mg²⁺, Mn²⁺, Cu²⁺ and Zn²⁺. The attachment of a cofactor with main enzyme (apoenzyme) changes the shape of protein and allows it to combine with substrate. Enzyme carbolic anhydrase, contains zinc the cytochromes contain iron and Troponin (a muscles contraction in enzyme) contains calcium. The cofactors of an enzyme participate in the temporary bonds between the enzyme and it substrate when the enzyme substrate complex forms.