1st product of tryptophan catabolism is?

ANSWER: (A) KynerunineREF: Harper's 27th ed ch: 29Tryptophanisdegradedto amphibolic intermediatesvia thekynurenine-anthranilate pathway. Tryptophan oxygenase (tryptophan pyrrolase) opens the indole ring, incorporates molecular oxygen, and forms N-formylkynurenine.Hydrolytic removal of the formyl group of AT-formylkynurenine, catalyzed by kynurenine formylase, produces kynurenine. Since kynureninase requires pyridoxal phosphate, excretion of xanthurenate in response to a tryptophan load is diagnostic of vitamin B6. deficiency.Hartnup disease reflects impaired intestinal and renal transport of tryptophan and other neutral amino acids.