This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Pyridoxine is involved in 
Select and explain. 
A. Carboxylation, B. Trans-sulfuration, C. Oxidation-reduction, D. Transketolation
B: Trans-sulfuration
Answer: B: Trans-sulfuration 
Explanation: Pyridoxine is involved in trans-sulfuration.Sulfur-Containing Amino Acids PLP plays an impoant role in methionine and cysteine metabolism. a.Homocysteine + Serine - Cystathionine. (Enzyme Cystathionine synthase) b.Cystathionine - Homoserine + Cysteine (Enzyme Cystathionase) Both these reactions require PLP. Here transfer of sulphur group occurs.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 396