ANTIBACTERIAL ACTIVITY OF GLYCOSYLATED AND PHOSPHORYLATED CHROMOGRANIN-A-DERIVED PEPTIDE-173-194 FROM BOVINE ADRENAL-MEDULLARY CHROMAFFIN GRANULES

Recently, we have isolated from bovine chromaffin granules and identif ied two natural peptides possessing antibacterial activity: secretolyt in (chromogranin B 614-626) and enkelytin (proenkephalin-A 209-237). H ere, we characterize a large natural fragment, corresponding to chromo granin A 79-431, that inhibits growth of both Gram-positive and Gram-n egative bacteria. The aim of the present work was to determine the sho rtest active peptide located in the 79-431 chromogranin A region. Thre e peptides, which shared the same 173-194 chromogranin A sequence (YPG PQAKEDSEGPSQGPASREK) but differed in post-translational modifications, including O-glycosylation and tyrosine phosphorylation, were isolated . A detailed study using microsequencing and mass spectrometry allowed us to correlate their antibacterial activity with these posttranslati onal modifications. The chromogranin A precursor fragment (79-431) and the active glycosylated and phosphorylated peptides were, respectivel y, named prochromacin and chromacin (P, G, and PG for phosphorylated, glycosylated, and phosphorylated-glycosylated form).