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

The partial purification and characterization of antimicrobial peptide (AMP) from the hemolymph ofcockroach, Periplaneta americana, was studied. Hemolymph was drawn from cockroach and the AMP waspurified on a sephadex G-75 gel filtration column. The gel filtration showed two peaks, I and II, and only peakII showed five active fractions, namely, 12, 13, 14, 15, and 16, of antimicrobial activity. Fraction 13 showedthe highest microbial Inhibition concentration (MIC) and a single protein band on SDS-PAGE(sodium dodecylsulfate–polyacrylamide gel electrophoresis) with a molecular mass of 60.2 kDa. Purified antimicrobial proteinexhibited 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 ofexposure. The study concludes that the AMP from hemolymph was effective against microbes or was able torecognize the molecular pattern of microorganisms

Partial purification and characterization of lectin from serum of American cockroach, Periplaneta americana

The partial purification and characterization of haemagglutinin (lectin) were carried out from the hemolymphof the adult American cockroach, Periplaneta americana. The hemolymph was drawn from cockroach andlectin was purified by a single-step method, using ammonium sulfate (NH4)2SO4 salt fractionation and gelfiltration. Gel filtration showed two peaks. The Hemagglutination Activity (HA) was observed in the 20thfraction of the second peak. The purified lectin showed a molecular weight of 26.8kDa on Sodium DodecylSulfate-Poly Acrylamide Gel Electrophoresis. The purified lectin showed an increase in HA at pH 7.5 and,subsequently, a sharp decline at pH 8. This indicates that HA was specific to a certain pH level. Similarly, anincrease in HA was observed until 30°C, followed by a decline at 40°C. This indicates the heat labile nature oflectin. The HA showed a higher specificity to divalent Ca2+ and showed no specificity for Ba2+. It also showeda higher inhibition for sugar D-galactose and a least inhibition for D-lactose. The HA to vertebrate blood groupshowed a highest activity to goat Red Blood Cells (RBCs). The study concludes that carbohydrate-bindingspecific lectin is important for recognition of the cell surface carbohydrate of invading pathogens