title: Structure-activity relationships of a pigment-dispersing crustacean neurohormone.
abstract: This study evaluated the effects of N-terminal sequence deletion and of chemical modifications on the melanophore pigment dispersing activity of a crustacean neuropeptide (DRPH: Asn-Ser-Gly-Met-Ile-Asn-Ser-Ile-Leu-Gly-Ile-Pro-Arg-Val-Met-Thr-Glu-Ala-NH2). Sustained biological activity was not demonstrated by peptides smaller than the tridecapeptide DRPH (6-18). N-terminal extension of this peptide led to a steady increase in activity, with the DRPH (1-18) showing the maximum activity. Carboxyl group modification had no effect, but acetylation, oxidation, cyanogen bromide, and trypsin caused a decrease in activity. Phenylglyoxal modification of Arg-13 in DRPH led to a 14-fold increase in activity. It is concluded that the N-terminus and the methionine residues are important for full activity and that the phenylglyoxal-induced potentiation is due to protection of the peptide from proteolysis in vivo.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D003386:Brachyura; D055598:Chemical Phenomena; D002621:Chemistry; D003445:Crustacea; D008547:Melanophores / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology*; D012168:Retinal Pigments / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D010455:Peptides; D012168:Retinal Pigments; C027714:melanophore-dispersing hormone