THE IDENTIFICATION OF 2 MYOINHIBITORY PEPTIDES, WITH SEQUENCE SIMILARITIES TO THE GALANINS, ISOLATED FROM THE VENTRAL NERVE CORD OF MANDUCA-SEXTA

Two new myoinhibitory peptides, Mas-MIP I and Mas-MIP II, were identif ied from the ventral nerve cord of the adult tobacco hornworm, Manduca sexta. Sequences obtained by a combination of automated Edman degrada tion and electrospray mass spectrometry were, respectively, AWQDLNSAW and GWQDLNSAW. The native peptides were found to co-elute with synthet ic C-terminal amides on a reverse phase HPLC system. When applied to i solated ilea (anterior hindgut) of adult M. sexta, both peptides were found to significantly reduce the rate of peristalsis, or abolish peri stalsis entirely, at concentrations of 1 . 10(-9) M. Both peptides sha re sequence similarities with Lom-MIP, a previously identified myoinhi bitory peptide from Locusta migratoria, and with the N-terminal portio n of vertebrate peptides in the galanin family.