Characterization and sequence elucidation of a novel peptide with molt-inhibiting activity from the South African spiny lobster, Jasus lalandii

We have isolated a peptide from extracts of sinus glands from a South Afric an Spiny lobster species, Jasus lalandii. by high-performance liquid chroma tography (HPLC) and identified it as a putative molt-inhibiting hormone (MI H) by (i) an in vitro assay with J. lalandii Y-organs to measure the inhibi tion of ecdysteroid synthesis and (ii) an immunoassay using antiserum raise d against MIH of the edible crab. The MIH of J. lalandii has 74 amino acid residues, a molecular mass of 9006 Da, a free N-terminus and an amidated C- terminus. The full primary sequence has been obtained from sequencing vario us digest fragments (tryptic, endoproteinase Asp-N, cyanogen bromide) of th e unreduced (native) peptide: RFTFDCPGMMGQRYLYEQVEQVCDDCYNLYREEKIAVNCRENCFL NSWFTVCLQATMREHETPRFDI WRSIILKA-NH2. Structural comparisons with other pept ides show that the J. lalandii MIH belongs to the peptide family which incl udes the crustacean hypeglycemic hormone, molt-inhibiting hormone and vitel logenesis-inhibiting hormone (cHH/MIH/VIH). This novel peptide has 36-43% s equence identity to putative MIHs from other decapod crustaceans and 32-34% identity to the two cHH peptides previously identified in this spiny lobst er species. This is the first report of a peptide with MIH activity in the Palinuridae infraorder. (C) 2000 Elsevier Science Inc. All rights reserved.