PHOTODEGRADATION OF TRYPTOPHAN IN WOOL

The amino acid tryptophan is degraded upon light exposure or during ac id and oxidative treatments. After irradiation of tryptophan solutions , the photodegradation products N'-formylkynurenine, kynurenine, trypt amine, and oxindolylalanine were identified by means of HPLC, These ph otoproducts of tryptophan contribute to the photoyellowing of wool. Ox ygen plays a major role in tryptophan photodegradation. An attack of o xygen at the indole residue initiates the photodegradation reaction. T he main photodegradation of tryptophan in proteins (e.g. in polytrypto phan or in wool) is the cleavage of the indole ring and the formation of kynurenines. In irradiated wool, only N'-formylkynurenine was detec ted. N'-Formylkynurenine is known to be a photosensitiser.