title: Chemical modification of the tryptophan residue in adrenocorticotropin.
abstract: The single tryptophan residue in the pituitary hormone adrenocorticotropin was modified selectively by reaction with a variety of substituted o-nitrophenylsulfenyl chlorides. In addition to quantitative modification of the tryptophan residue, the reaction invariably resulted in partial oxidation of the methionine residue to the sulfoxide. The methionine sulfoxide derivative could be separated from the desired product by partition chromatography on Sephadex G-50 in the solvent system 1-butanol-pyridine-0.1% acetic acid (5:3:11). Thus, the 2,4-dinitrophenylsulfenyl, 2-nitro-4-carboxyphenylsulfenyl, and 2-nitro-4-carbamidophenylsulfenyl derivatives of adrenocorticotropin were prepared and characterized. Modifications in the isolation of adrenocorticotropin from ovine pituitaries are also described. The melanocyte stimulating activities of the native hormone and the analogues are discussed.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000032:analysis / Q000494:pharmacology; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001001:Anura; D001681:Biological Assay; D055598:Chemical Phenomena; D002621:Chemistry; D008544:Melanocytes / Q000187:drug effects; D010446:Peptide Fragments / Q000032:analysis; D010902:Pituitary Gland / Q000032:analysis; D051381:Rats; D012756:Sheep; D013256:Steroids / Q000096:biosynthesis; D013329:Structure-Activity Relationship; D013434:Sulfenic Acids; D014364:Tryptophan
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D013256:Steroids; D013434:Sulfenic Acids; D014364:Tryptophan; D000324:Adrenocorticotropic Hormone