title: Preparation of photoreactive derivatives of glutathione and [9-(2-mercaptotryptophan)]corticotropin by selective modification of the sulfhydryl group.
abstract: The photoreactive arylsulfenyl chlorides 2-nitro-4-azidophenylsulfenyl chloride (2,4-NAPS-Cl) and 2-nitro-5-azidophenylsulfenyl chloride (2,5-NAPS-Cl) have been used for the selective modification of thiol groups in glutathione and [Trp(SH)9]corticotropin (ACTH). Both reagents reacted rapidly with both types of thiol groups to form unsymmetrical disulfides. The photoreactive derivatives of glutathione and [Trp(SH)9]ACTH were stable to neutral and acidic conditions but were readily cleaved above pH 9 and by beta-mercaptoethanol. Photolysis of the NAPS derivatives of [Trp(SH)9]-ACTH at neutral pH resulted in the formation of covalently liked polymers and dimers which yielded monomer upon treatment with beta-mercaptoethanol. Analysis of the amino acid composition of acid hydrolysates of photolysed monomeric and dimeric products indicated a decrease in proline, valine, tyrosine, and phenylalanine.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives*; D000345:Affinity Labels; D000596:Amino Acids / Q000032:analysis; D001386:Azides; D004220:Disulfides; D005978:Glutathione / Q000031:analogs & derivatives*; D007202:Indicators and Reagents; D007700:Kinetics; D008722:Methods; D013053:Spectrophotometry
chemical_list: D000345:Affinity Labels; D000596:Amino Acids; D001386:Azides; D004220:Disulfides; D007202:Indicators and Reagents; C027146:2-nitro-4-azidophenylsulfenyl chloride; D000324:Adrenocorticotropic Hormone; D005978:Glutathione