<prompt> All of the following vitamins are involved in sulphur containing amino acid metabolism except?Vitamin B3Vitamin B6Vitamin B9Vitamin B12  <response>: Vitamin B6, B9 and B12 are involved in sulphur containing amino acid metabolism. Vitamin B6 Pyridoxine is the co-enzyme of cystathionine b synthase. Vitamin B9 Folic acid and B12 Cobalamin are involved in the conversion of homocysteine to methionine by methionine synthase. Clinical impoance: Reference: Harpers illustrated biochemistry 30th edition 