蛋白酶抑制剂对杨扇舟蛾的中肠蛋白酶作用的研究(英文)

EFFECT OF PROTEINASE INHIBITORS ON THE MIDGUT PROTEINASE OF CLOSTERA ANACHORETA LARVAE

研究了杨扇舟蛾幼虫的中肠几种主要蛋白酶活性．以14C-酪蛋白为底物测定的总消化酶活性在碱性缓冲液中最高；特异蛋白酶抑制剂研究表明：只有丝氨酸蛋白酶抑制剂对中肠蛋白酶活性有抑制作用，其它的特异蛋白酶抑制剂如半光氨酸蛋白酶抑制剂、天门冬氨酸蛋白酶抑制剂和金属蛋白酶抑制剂对中肠的酶活均无抑制作用，可以认为杨扇舟蛾的中肠蛋白酶以丝氨酸蛋白酶为主．以特异的p－nitroanilide为底物测定胰蛋白酶、胰凝乳蛋白酶、弹性蛋白酶和亮氨酸蛋白酶活性在碱性缓冲液中最高，且以弹性蛋白酶活性最高．在所研究的23个丝氨酸蛋白酶抑制剂中，抑制作用最强的是马铃薯蛋白酶抑制剂I和南瓜韧皮胰蛋白酶抑制剂．本研究丰富了对杨扇舟蛾的中肠蛋白酶种类的了解，为杨树抗虫基因构建和转化提供了依据．

The major proteinase activities in the larval midgut of Clostera anachoreta were characterized. Overall digestive capacity which was measured by casein hydrolysis showed a alkaline pH optimum and serine proteinase activity. The abences of cysteine, aspartic acid and metallo-proteinases were confirmed by specific proteinase inhibitors. Trypsin,chymotrypsin, leucine aminopeptidase and elastase-like activities were detected using specific p-nitroanilide synthetic substrates.These enzyme activities also showed pH optima in the alkaline range. The dominant proteinase in the midgut was elastase. 23 serine proteinase inhibitors were screened and varied widely in their ability to inhibit casein hydrolysis. potato proteinase inhibitor 1 and pumpkin fruittrypsin inhibitor were the most effective,and represent the possible candidates for gene transformation to produce plants tolerant to this pest.