De novo sequencing of antimicrobial peptides isolated from the venom glands of the wolf spider Lycosa singoriensis

Antimicrobial peptides (AMPs), named lycocitin 1, 2 and 3, and a peptide with a monoisotopic molecular mass of 3038.70 Da were detected in the venom glands of the wolf spider Lycosa singoriensis . Two of the peptides, lycocitin 1 and 2, are new AMPs whereas lycocitin 3 is highly homologous to lycotoxin II isolated from the venom of spider Lycosa carolinensis . In addition, two other peptides with monoisotopic masses of 2034.20 and 2340.28 Da showing the motif typical for antimicrobial peptides were also identified. These peptides and lycocitin 1, 2 and 3 were de novo sequenced using electron capture dissociation and low‐energy collisional tandem mass spectrometry. The amino acid sequence of lycocitin 1 was determined as GKLQAFLAKMKEIAAQTL‐NH 2 . Lycocitin 2 differs from lycocitin 1 by a replacement of a lysine residue for an arginine residue at the second position. Lycocitin 3 differs from the known lycotoxin II consisting of 27 amino acid residues by a deletion of Gly‐26. Both lycocitin 1 and 2 inhibit growth of Gram‐positive ( Staphylococcus aureus, Bacillus subtilis ) and Gram‐negative ( Escherichia coli ) bacteria and fungi ( Candida albicans, Pseudomonas aeruginosa ) at micromolar concentrations. Copyright © 2004 John Wiley & Sons, Ltd.