Calcitermin, a novel antimicrobial peptide isolated from human airway secretions

The human airways are protected from pathogenic colonization by a blanket o f fluid impregnated with innate antimicrobial effector molecules. Among sev eral previously uncharacterized components, we isolated a peptide that had activity primarily targeting Gram-negative bacteria. We named the peptide ' calcitermin' since its amino acid sequence and mass were equivalent to the 15 C-terminal residues of the S100 protein, calgranulin C. The antimicrobia l activity of calcitermin was enhanced in acidic buffers (pH 5.4) and in th e presence of micromolar concentrations Of ZnCl2. Analysis revealed a putat ive zinc-binding consensus sequence as well as an alpha -helical conformati on in structure-promoting solvents. (C) 2001 Federation of European Biochem ical Societies. Published by Elsevier Science B.V. All rights reserved.