1. Sulphate conjugation  A sulphate molecule is transferred from the cofactor (3`-phosphoadenosine 5`- phosphosulphate, PAPS) to the substrate by enzymes known as sulfotransferases.

2. Conjugation Reactions Sulfation (3`- phosphoad enosine 5`- phosphosul phate( PAPS)

3. Examples   ethanol   p-hydroxyacetanilide   3-hydroxycoumarin

5. Sulfation may produce active metabolites

6. Conjugation Reactions Acetylation

7.  The transfer of acetyl group takes place in presence of N-acetyl transferases.  In acetylation although water solubility is not increased, it helps in terminating the pharmacological activity of the drug or its amino metabolite.

8. Examples: Procainamide, isoniazid, sulfanilimide, histamine NAT (N-Acetyl transferase)enzyme is found in many tissues, including liver.

10. Isoniazide

11. Amino acid conjugation Cinnamic acid

12. Glycine is the most common amino acid used for conjugation, while a few glutamine conjugates have been identified in humans.