title: Toxicity of L-Tryptophan photoproduct on recombinationless (rec) mutants of Salmonella typhimurium.
abstract: l-Tryptophan after exposure to black light becomes toxic for recombinationless (rec) mutants of Salmonella typhimurium. Fifty-six radiation-sensitive mutants were screened for sensitivity to the tryptophan photoproduct; the rec and exr (X-ray sensitive) mutants are sensitive, whereas the uvr, hcr, and wild-type strains are resistant. A number of catabolic products of tryptophan and compounds related to tryptophan were screened for toxicity to rec strain; these are nontoxic or far less toxic for rec strains than irradiated l-tryptophan. The toxic photoproduct is relatively stable to drying and basic hydrolysis at 90 C, indicating that it is a stable organic compound, eliminating peroxide as the toxic component. It was also observed that the toxic product is a photooxidation product since it is formed only when l-tryptophan is irradiated in the presence of air.
mesh_terms: D003470:Culture Media; D008027:Light; D009154:Mutation; D011830:Radiation Effects; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development; D013237:Stereoisomerism; D014364:Tryptophan / Q000494:pharmacology* / Q000528:radiation effects
chemical_list: D003470:Culture Media; D014364:Tryptophan