Amino acid sequence of crustacean hyperglycemic hormone (CHH) from the crayfish, Orconectes limosus: emergence of a novel neuropeptide family.

The primary structure of the major form of CHH from sinus glands of the crayfish, Orconectes limosus, was determined by manual Edman microsequencing. It is a 72-residue peptide with a calculated Mr of 8400 Da. In the number of residues, it is identical to the CHH of Carcinus maenas and very similar to MIH (moult inhibiting hormone) of Homarus americanus. All three peptides have pGlu as N-terminus in common, and Val-NH2 is the C-terminal residue in Orconectes and Carcinus CHH. Six Cys residues occupy identical position in the three peptides. There is a 61% sequence identity with Carcinus CHH, and an 81% identity with Homarus MIH.