Lockey T D, Ourth D D
Department of Biology, Division of Molecular Sciences and Microbiology, The University of Memphis, Tennessee 38152, USA.
Biochem Biophys Res Commun. 1996 Mar 27;220(3):502-8. doi: 10.1006/bbrc.1996.0434.
Lysozyme is an important antibacterial protein in the insect defense system. Lysozyme was isolated from hemolymph of Heliothis virescens larvae using gel filtration and ion-exchange chromatography. Heliothis lysozyme 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 three Gram-positive bacteria but no activity against Escherichia coli. The 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 min incubation. Heliothis lysozyme was an inducible protein that increased 9 times when comparing unvaccinated with vaccinated larvae. Lysozyme from H. virescens was more similar in molecular mass, heat sensitivity and pH sensitivity to lysozyme isolated from Galleria mellonella and Bombyx mori than to lysozyme isolated from Hyalophora cecropia.
溶菌酶是昆虫防御系统中的一种重要抗菌蛋白。利用凝胶过滤和离子交换色谱法从烟青虫幼虫的血淋巴中分离出溶菌酶。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）测定，烟青虫溶菌酶的分子量为16,000道尔顿。采用酸性凝胶电泳时，烟青虫溶菌酶的迁移速度比蛋清溶菌酶快。烟青虫溶菌酶的等电点估计大于9.5。烟青虫溶菌酶对三种革兰氏阳性菌具有特异性杀菌活性，但对大肠杆菌无活性。在pH 3.0条件下于100℃孵育60分钟后，杀菌活性稳定，但在pH 6.8条件下于100℃孵育60分钟后，杀菌活性不稳定。烟青虫溶菌酶是一种诱导型蛋白，与未接种疫苗的幼虫相比，接种疫苗的幼虫体内该蛋白含量增加了9倍。与从樗蚕中分离出的溶菌酶相比，烟青虫的溶菌酶在分子量、热敏感性和pH敏感性方面与从大蜡螟和家蚕中分离出的溶菌酶更为相似。
