Boigegrain R A, Pugnière M, Paroutaud P, Castro B, Brehélin M
Laboratoire de Pathologie Comparée, INRA-CNRS, UMR 5087, Montpellier, France.
Insect Biochem Mol Biol. 2000 Feb;30(2):145-52. doi: 10.1016/s0965-1748(99)00109-5.
A low molecular weight protease inhibitor peptide found in ovaries of the desert locust Schistocerca gregaria (SGPI-2), was purified from plasma of the same locust and sequenced. It was named SGCI. It was found active towards chymotrypsin and human leukocyte elastase. SGCI was synthesized using a solid-phase procedure and the sequence of its reactive site for chymotrypsin was determined. Compared with an inhibitor purified earlier from another locust species, the total sequence of SGCI showed 88% identity. In particular, the sequence of the reactive site of these inhibitors was identical. Our search for a closely related peptide in an insect species far removed from locusts, the lepidopteran Spodoptera littoralis, was unfruitful but a different chymotrypsin inhibitor, belonging to the Kazal family, was found whose mass is greater than that of SGCI (20 vs 3.6 kDa). Its N-terminal sequence shares 80% identity with that of a chymotrypsin inhibitor purified earlier from the haemolymph of another lepidopteran. Conservation of the amino acid sequence in the reactive site seems to be an exception among protease inhibitors.
从沙漠蝗（Schistocerca gregaria）卵巢中发现的一种低分子量蛋白酶抑制肽（SGPI-2），从同一种蝗虫的血浆中纯化并测序。它被命名为SGCI。发现它对胰凝乳蛋白酶和人白细胞弹性蛋白酶有活性。使用固相方法合成了SGCI，并确定了其对胰凝乳蛋白酶的反应位点序列。与先前从另一种蝗虫中纯化的抑制剂相比，SGCI的总序列显示出88%的同一性。特别是，这些抑制剂的反应位点序列是相同的。我们在与蝗虫亲缘关系较远的昆虫物种——鳞翅目昆虫草地贪夜蛾（Spodoptera littoralis）中寻找密切相关肽的尝试没有成功，但发现了一种不同的属于Kazal家族的胰凝乳蛋白酶抑制剂，其质量大于SGCI（分别为20 kDa和3.6 kDa）。其N端序列与先前从另一种鳞翅目昆虫血淋巴中纯化的胰凝乳蛋白酶抑制剂的N端序列有80%的同一性。反应位点氨基酸序列的保守性在蛋白酶抑制剂中似乎是个例外。
