Cecropins, inducible antibacterial peptides, were purified by simple two step chromatography from immunized larval hemolymph of the silkworm, Bombyx mori. 2. The cecropins were further separated into four major and two minor forms by reverse-phase HPLC. 3. The four major cecropins were sequenced and divided into two types, A and B, whose structures were quite similar to cecropins A and B of Hyalophora cecropia. 4. Three of them contained an unusual amino acid, delta-hydroxylysine. 5. No remarkable difference in antibacterial activity against E. coli was detected among these cecropins.
