Partial purification and characterization of antimicrobial peptide from the hemolymph of cockroach Periplaneta americana

Abstract

The partial purification and characterization of antimicrobial peptide (AMP) from the hemolymph of cockroach, Periplaneta americana, was studied. Hemolymph was drawn from cockroach and the AMP was purified on a sephadex G-75 gel filtration column. The gel filtration showed two peaks, I and II, and only peak II showed five active fractions, namely, 12, 13, 14, 15, and 16, of antimicrobial activity. Fraction 13 showed the highest microbial Inhibition concentration (MIC) and a single protein band on SDS-PAGE(sodium dodecyl sulfate–polyacrylamide gel electrophoresis) with a molecular mass of 60.2 kDa. Purified antimicrobial protein exhibited the highest antimicrobial activity against Escherichia coli at 30°C, pH 6.0, and 5 mM calcium ion. The AMP showed higher activity of MIC against lipopolysaccharides and β-1,3 glucan during 5 hours of exposure. The study concludes that the AMP from hemolymph was effective against microbes or was able to recognize the molecular pattern of microorganisms.