Functional aspects of cHH C-terminal amidation in crayfish species

The crustacean hyperglycemic hormone is the most abundant neuropeptide present in the eyestalk of Crustacea and its main role is to controlthe glucose level in the hemolymph. Our study was aimed at assessing the importance of C-terminal amidation for its biological activity. Tworecombinant peptides were produced, Asl-rcHH-Gly with a free carboxyl terminus and Asl-rcHH-amide with an amidated C-terminus.Homologous bioassays performed on the astacid crayfish Astacus leptodactylus showed that the amidated peptide had a stronger hyperglycemiceffect compared to the non-amidated peptide. To assess the relevance of amidation also in other decapods and how much the differences in thecHH amino acid sequence can affect the functionality of the peptides, we carried out heterologous bioassays on the cambarid Procambarus clarkiiand palaemonid Palaemon elegans. The Asl-rcHH-amide elicited a good response in P. clarkii and in P. elegans. The injection of Asl-rcHH-Glyevoked a weak response in both species. These results prove the importance of C-terminal amidation for the biological activity of cHH in crayfishas well as the role of the peptide primary sequence for the species-specificity hormone-receptor recognition.© 2008 Elsevier B.V. All rights reserved.