Elucidation of the amino acid sequence of a crustacean hyperglycaemic hormone from the spiny lobster, Jasus lalandii

Abstract

We have isolated a peptide from extracts of sinus glands of Jasus lalandii, a South African spiny lobster, by high-performance liquid chromatography (HPLC) and identified it as crustacean hyperglycaemic hormone (cHH) by (i) a conspecific bioassay measuring glucose elevation in the haemolymph and (ii) an immunoassay using an antiserum raised against cHH of the American lobster. The J. lalandii peptide has a free N-terminus as evidenced by sequencing the first 30 amino acid residues of the intact peptide. Further primary structural data were obtained from sequencing HPLC-purified tryptic and Asp-N proteolytic digests and by cyanogen bromide cleavage of the native, unreduced peptide. In this way, less than 400 sinus glands were used to provide the full sequence. Mass spectrometric analysis in conjunction with inferences based on interspecies sequence homology of cHH molecules unequivocally assigned the complete primary structure of cHH in a member of the crustacean infraorder Palinura for the first time. Our results show 51-76% homology with cHHs known from other decapod infraorders, the major difference being a free N-terminus and several amino acid substitutions interspersed in the non-conserved regions of the molecule. The J. lalandii cHH sequence presented here differs from a partial cHH sequence previously reported from allegedly the same species.