Catch-relaxing peptide isolated from Mytilus pedal ganglia

Abstract A peptide that relaxes catch tension of the anterior byssus retractor muscle of Mytilus edulis was purified from pedal ganglion extracts of the mussel. Its primary structure was determined to be H-Ala-Met-Pro-Met-Leu-Arg-Leu-NH 2 . This peptide was found to have not only catch-relaxing action on the byssus retractor muscle but also modulatory actions on contractions in various molluscan muscles.