PURIFICATION AND CHARACTERIZATION OF LYSOZYME FROM HEMOLYMPH OF HELIOTHIS-VIRESCENS LARVAE

Lysozyme is an important antibacterial protein in the insect defense s ystem. Lysozyme was isolated from hemolymph of Heliothis virescens lar vae using gel filtration and ion-exchange chromatography. Heliothis ly sozyme had a molecular mass of 16,000 daltons by SDS-PAGE. Using acid gel electrophoresis, Heliothis lysozyme migrated faster than egg white lysozyme. The pi of Heliothis lysozyme was estimated as greater than 9.5. Heliothis lysozyme had specific bactericidal activity against thr ee Gram-positive bacteria but no activity against Escherichia coil. Th e bactericidal activity was stable at 100 degrees C at pH 3.0 after 60 min incubation, but was labile at 100 degrees C at pH 6.8 after 60 mi n incubation. Heliothis lysozyme was an inducible protein that increas ed 9 times when comparing unvaccinated with vaccinated larvae. Lysozym e from H. virescens was more similar in molecular mass, heat sensitivi ty and pH sensitivity to lysozyme isolated from Galleria mellonella an d Bombyx mori than to lysozyme isolated from Hyalophora cecropia. (C) 1996 Academic Press, Inc.