Nicholls C N, Ahmad W, Ellar D J
Department of Biochemistry, University of Cambridge, United Kingdom.
J Bacteriol. 1989 Sep;171(9):5141-7. doi: 10.1128/jb.171.9.5141-5147.1989.
Analysis of polypeptides in the crystalline delta-endotoxins from different Bacillus thuringiensis strains revealed two antigenically similar forms of the P2 protein which differed in molecular mass, peptide profile, and amino acid sequence. Purified preparations of the two forms displayed the characteristic dual toxicity of the P2 protein towards members of the orders Lepidoptera and Diptera in vivo but differed markedly in potency for the insects tested. Both species of the P2 protoxin, solubilized and activated by sequential proteolysis with insect gut extract and alpha-chymotrypsin, retained activity in vivo and in vitro, despite the removal of 144 residues from the N terminus. For the low-molecular-mass form, the dual insecticidal activity was reproducible in the in vitro assays.
对来自不同苏云金芽孢杆菌菌株的晶体δ-内毒素中的多肽进行分析，发现P2蛋白有两种抗原性相似的形式，它们在分子量、肽谱和氨基酸序列上存在差异。两种形式的纯化制剂在体内均表现出P2蛋白对鳞翅目和双翅目昆虫的典型双重毒性，但对所测试昆虫的效力有显著差异。P2原毒素的两种形式经昆虫肠道提取物和α-胰凝乳蛋白酶顺序蛋白水解而溶解并激活，尽管从N端去除了144个残基，但在体内和体外均保留活性。对于低分子量形式，其双重杀虫活性在体外试验中具有可重复性。
