Substitution of norleucine for methionine residues in a crustacean pigment-dispersing hormone.
In order to evaluate the structural/functional roles of Met residues in an octadecapeptide pigment-dispersing hormone (PDH: Asn-Ser-Gly-Met-Ile-Asn-Ser-Ile-Leu-Gly-Ile-Pro-Arg-Val-Met-Thr-Glu-Ala- NH2), first described as light-adapting distal retinal pigment hormone (DRPH) from Pandalus, three analogs were synthesized: Nle4-PDH, Nle15-PDH, and Nle4,15-PDH. When tested for melanophore pigment-dispersing activity in destalked Uca, all three Nle-analogs were more potent than unsubstituted PDH. Performic acid oxidation caused a marked loss of potency of PDH, Nle4-PDH, and Nle15-PDH. The analog Nle4,15-PDH was resistant to oxidation and displayed 6-fold higher potency than PDH. Thus Met4 and Met15 are not essential for the PDH activity. The oxidation-induced loss of activity of unsubstituted PDH may result from introduction of oxygen (in methionine sulfone) and a consequent conformational change in the octadecapeptide.
D000614:Aminocaproates; D000818:Animals; D003445:Crustacea / Q000502:physiology; D007301:Insect Hormones / Q000138:chemical synthesis* / Q000494:pharmacology; D008547:Melanophores / Q000187:drug effects; D008715:Methionine; D009490:Neurosecretory Systems / Q000502:physiology; D009646:Norleucine; D010084:Oxidation-Reduction; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D011487:Protein Conformation; D012880:Skin Pigmentation; D013329:Structure-Activity Relationship
D000614:Aminocaproates; D007301:Insect Hormones; D010455:Peptides; D009646:Norleucine; C027714:melanophore-dispersing hormone; D008715:Methionine