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EFFECT OF VISIBLE LIGHT ON AMINO ACIDS—I. TRYPTOPHAN
Author(s) -
Gurnani Shantoo,
Arifuddin M.,
Augusti K. T.
Publication year - 1966
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1966.tb09839.x
Subject(s) - tryptophan , tryptamine , chemistry , indole test , methylene blue , anthranilic acid , amino acid , photochemistry , visible spectrum , hydrogen peroxide , kynurenine , tryptophanase , aldehyde , ultraviolet light , organic chemistry , biochemistry , catalysis , physics , optoelectronics , photocatalysis
Abstract— Seven chromatographically separable products were shown to be formed when an aqueous solution of tryptophan was exposed to the light of a 100‐W bulb at pH 9 in the presence of methylene blue and oxygen. Some of these products were detected, though in much smaller quantities, even when tryptophan was irradiated in the absence of methylene blue and/or oxygen. Contrary to reports in the literature, none of the common derivatives of tryptophan, such as tryptamine, indole acetic acid, indole aldehyde, anthranilic acid or kynurenine, were detected on irradiation of the amino acid by visible light. Such irradiation of tryptamine and indole acetic acid gave 1–2 components which were chromatographically identical with those obtained from tryptophan; irradiation of indole aldehyde gave no detectable breakdown products. Exposure of tryptophan to ultraviolet light or when treated with hydrogen peroxide did not result in the formation of any of the products obtained with visible light. The results presented here suggest that during exposure of tryptophan to visible light, the indole ring is first oxygenated resulting in the formation of dioxindole derivatives. One of the products of irradiation of tryptophan with visible light was tentatively identified as dioxin‐dolylalanine.