Antibacterial protein induced in insect

将活的或热灭活的细菌注射到家蚕幼虫体内，可诱导血淋巴中的抗菌活性。虽然注射细菌没有诱导抗菌活性的特异性，但酵母细胞、真菌孢子和生理盐水单独作为诱导剂并不能有效地诱导抗菌活性，在天然聚丙烯酰胺凝胶电泳法上至少可以分离出6条对胰酶敏感的条带。用CM-纤维素柱层析分离得到的抗菌活性与溶菌酶活性相分离。其中两种蛋白(AP-A和AP-B)经纯化后均一。它们具有热稳定性，表现出天蚕素的特征性质。这些蛋白质在0.1ug/ml的浓度下对各种细菌的生长有抑制作用。

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.