Coenzymes

• A cofactor is a non-protein compound required for the enzyme’s activity to occur. There are three types of cofactors: coenzymes, activators and prosthetic groups.
• Coenzymes are organic cofactors which do not bind permanently. They facilitate the binding of substrate to enzyme. Many coenzymes are vitamin derived, examples include NAD derived from niacin, which acts as a hydrogen acceptor.
• Activators are inorganic metal ions which temporarily binds to the enzyme and alters its active site, making the reaction more feasible. For instance, magnesium ion is an important activator which is involved in processes such as shielding negative charge.
• Prosthetic groups are permanently attached to the enzyme. For instance, haemoglobin contains a prosthetic haem group which contains iron, permanently bound to the molecule, which serves as a means of binding oxygen.