Complete primary structure of the molt-inhibiting hormone (MIH) of the Mexican crayfish Procambarus bouvieri (Ortmann)

The amino acid sequence of MM was elucidated by means of digestions with specific proteases, manual Edman degradation, and mass spectrometry. MM consists of a 72-residue peptide chain (molecular mass 8322 Da) with six cysteines forming three disulfide bridges that connect residues 7-43, 23-39, and 26-52. It has blocked N- and C-termini and lacks tryptophan, histidine, and methionine. MM shows striking similarity to the crustacean hyperglycemic hormone (CHH) isomorphs of Procambarus bouvieri (90% identity) and to the MIH from Homarus americanus (79% identity) and Penaeus vannamei (46% identity). It is also related to the MM from Carcinus maenas (28% identity) and Callinectes sapidus (28% identity).