AMINO-ACID-SEQUENCE OF CAP(2B), AN INSECT CARDIOACCELERATORY PEPTIDE FROM THE TOBACCO HAWKMOTH MANDUCA-SEXTA

The primary structure of a novel insect neuropeptide, Cardioaccelerato ry Peptide 2b (CAP(2b)), from the tobacco hawkmoth Manduca sexta has b een established using a combination of mass spectroscopy, Edman degrad ation microsequencing, amino acid analysis, and biological assays, The sequence of CAP(2b), pyroGlu-Leu-Tyr-Ala-Phe-Pro-Arg-Val-amide has a molecular weight of 974.6 and is blocked at both the amino and carboxy l ends, Examination of several national computer protein data bases fa iled to reveal other peptides or proteins with any sequence homology t o CAP(2b) indicating that this is likely to be a novel insect neuropep tide. This peptide may be a general activator of insect viscera since it causes an increase in heart rate in Manduca and in Drosophila, and has also been implicated in the regulation of fluid secretion by the M alphigian tubules of Drosophila.