CHARACTERIZATION OF NOVEL CYSTEINE-RICH ANTIMICROBIAL PEPTIDES FROM SCORPION BLOOD

We have isolated, from the hemolymph of unchallenged scorpions of the species Androctonus australis, three distinct antimicrobial peptides, which we have fully characterized by Edman degradation, electrospray i onization mass spectrometry, and matrix-assisted laser desorption/ioni zation mass spectrometry. Two are novel molecules: (i) androctonin, a 25-residue peptide with two disulfide bridges, active against both bac teria (Gram-positive and Gram-negative) and fungi and showing marked s equence homology to tachyplesins and polyphemusins from horseshoe crab s; and (ii) buthinin, a 34-residue antibacterial (Gram-positive and Gr am-negative) peptide with three disulfide bridges. The third peptide c ontains 37 residues and three disulfide bridges and clearly belongs to the family of anti-Gram-positive insect defensins, We have synthesize d androctonin and explored its activity spectrum and mode of action.