Oppert B, Kramer K J, Johnson D, Upton S J, Mcgaughey W H
U.S. Grain Marketing Research Laboratory, ARS-USDA, Manhattan, KS 66502-2736, USA.
Insect Biochem Mol Biol. 1996 Jun;26(6):571-83. doi: 10.1016/s0965-1748(96)00013-6.
The ability of proteinases in gut extracts of the Indianmeal moth, Plodia interpunctella, to hydrolyze Bacillus thuringiensis (Bt) protoxin, casein, and rho-nitroanilide substrates was investigated. A polyclonal antiserum to protoxin CryIA(c) was used in Western blots to demonstrate slower protoxin processing by gut enzymes from Bt subspecies entomocidus-resistant larvae than enzymes from susceptible or kurstaki-resistant strains. Enzymes from all three strains hydrolyzed N-alpha-benzoyl-L-arginine rho-nitroanilide, N-succinyl-ala-ala-pro-phenylalanine rho-nitroanilide, and N-succinyl-ala-ala-pro-leucine rho-nitroanilide. Zymograms and activity blots were used to estimate the apparent molecular masses, number of enzymes, and relative activities in each strain. Several serine proteinase inhibitors reduced gut enzyme activities, with two soybean trypsin inhibitors, two potato inhibitors, and chymostatin the most effective in preventing protoxin hydrolysis.
研究了印度谷螟（Plodia interpunctella）肠道提取物中的蛋白酶水解苏云金芽孢杆菌（Bt）原毒素、酪蛋白和对硝基苯胺底物的能力。在蛋白质印迹中使用针对原毒素CryIA(c)的多克隆抗血清，以证明来自对Bt亚种entomocidus有抗性的幼虫的肠道酶对原毒素的加工速度比对敏感或对库尔斯塔克有抗性的菌株的酶慢。来自所有三个菌株的酶都能水解N-α-苯甲酰-L-精氨酸对硝基苯胺、N-琥珀酰-丙氨酸-丙氨酸-脯氨酸-苯丙氨酸对硝基苯胺和N-琥珀酰-丙氨酸-丙氨酸-脯氨酸-亮氨酸对硝基苯胺。酶谱和活性印迹用于估计每个菌株中蛋白酶的表观分子量、酶的数量和相对活性。几种丝氨酸蛋白酶抑制剂降低了肠道酶的活性，其中两种大豆胰蛋白酶抑制剂、两种马铃薯抑制剂和抑糜酶素在防止原毒素水解方面最有效。
