Tryptophan is required for synthesis of which vitamin?

Tryptophan is required for the synthesis of Niacin. In the major pathway, kynureninase is an enzyme dependent on pyridoxal phosphate (enzyme 2, Fig.17.8). Therefore, in vitamin B6 deficiency, the pathway is blocked at this level. This leads to niacin deficiency and manifestations of pellagra. 7. Quinolinate phosphoribosyl transferase is the rate-limiting enzyme in the conversion of niacin to NAD+. About 60 mg of tryptophan is equivalent to 1 mg of niacin. Reference: Vasudevan Textbook of Biochemistry pg no. 211, 395