Antibacterial protein induced in insect

将活菌或热灭活菌注入家蚕幼虫体内，可诱导家蚕血淋巴产生抗菌活性。虽然注射细菌对抗菌活性的诱导没有特异性，但酵母细胞、真菌孢子和生理盐水单独作为诱导剂均无效，其抗菌活性在聚丙烯酰胺凝胶电泳上至少可分离出6条对胰蛋白酶敏感的条带。用CM-纤维素柱层析法分离了抗菌活性和溶菌酶活性。其中两种蛋白质（AP-A和AP-B）被纯化至表观均一性。它们是热稳定的，并显示出天蚕素的特性。蛋白质在0.1 μ g/ml的浓度下抑制各种细菌的生长。

Injection of live or heat-killed bacteria into larvae of the silkworm, Bombyx mori induced antibacterial activities in the hemolymph. Although there was no specificity of injected bacteria for the induction of antibacterial activity, yeast cells, fungus spores and saline alone were not effective as inducing agent.The antibacterial activities were separated into at least six bands on native poly-acrylamide gel electrophoresis, which were sensitive to trypsin. The antibacterial activities were separated from lysozyme activity on CM-cellulose column chromatography. Two of these proteins (AP-A and AP-B) were purifies to apparent homogenity. They were heat-stable and showed characteristic properties of cecropins. The proteins repressed growth of various bacteria at a concentration of 0.1 ug/ml.