Nicotinamide is derived from: (A) Histidine, (B) Methionine, (C) Tryptophan, (D) Phenylalanine
Answer is C. The enzyme QP Is the rate limiting step in the formation of nicotinamide from Tryptophan.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 240