Amino acid sequence of CAP37, a human neutrophil granule-derived antibacterial and monocyte-specific chemotactic glycoprotein structurally similar to neutrophil elastase.

We report the amino acid sequence of CAP37, a human neutrophil granule protein with antibacterial and monocyte-specific chemotactic activity. CAP37 is a single-chain protein consisting of 222 amino acid residues. It has three N-glycosylation sites, at Asn residues 100, 114 and 145. Some species of CAP37 are glycosylated at all three sites; some at Asn-114 alone, others at Asn-114 and Asn-110 or Asn-145. CAP37 has 45% sequence identity to human neutrophil elastase, and 30-37% identity to several other granule serine proteinases. Despite these similarities, CAP37 is not a serine proteinase because the active site residues serine and histidine are replaced.