Eosinophil Chemotactic Peptide Sequences in Rat α‐CGRP: Activation of a Novel Trophic Action by Neutral Endopeptidase 24.11a

Abstract

Rat alpha- and alpha-CGRP are substrates for endopeptidase 24.11 in vitro. Cleavage of both peptides occurs at several points, including an unusual substrate recognition site to the amino side of ala36. In alpha-CGRP this resulted in the early formation of val32-gly-ser-glu35, a sequence previously reported to be a component of the eosinophil chemotactic factor of anaphylaxis (ECF-A). The biological activity of this peptide fragment was confirmed by bioassay. Chemotactic activity in other hydrolysis fragments of both alpha- and beta-CGRP was observed. Both alpha- and beta-CGRP could thus serve as precursors to different eosinophil chemotactic peptide fragments. A novel function of endopeptidase 24.11 may be to modify rather than to terminate the biological activity of CGRP peptides.