麻蝇幼虫肠道类胰蛋白酶的分离纯化及性质(英文)

麻蝇幼虫肠液经硫铵沉淀， ＤＥＡＥ－Ｓｅｐｈａｄｅｘ Ａ－２５离子交换层析， ＳＢＢＩ－Ｓｅｐｈａｒｏｓｅ ４Ｂ亲和层析，分离纯化出一种分子量为 １６ｋＤ的蛋白酶。底物及抑制剂的特异性表明，该酶为类胰蛋白酶。其能够强烈地降解蛋白酶非专一底物酪蛋白和 Ｈｉｄｅ ｐｏｗｄｅｒ ａｚｕｒｅ，以及类胰蛋白酶专一底物 Ｂｚ－Ｐｈｅ－Ｖａｌ－Ａｒｇ ＮＡ， Ｂｚ－Ｐｒｏ－Ｐｈｅ－Ａｒｇ ＮＡ和Ｂｚ－Ｖａｌ－Ｇｌｙ－Ａｒｇ ＮＡ．该酶又能被丝氨酸蛋白酶抑制剂ＰＭＳＦ，类胰蛋白酶抑制剂 ＳＢ－ＢＩ和Ｌｅｕｐｅｐｔｉｎ强烈地抑制。蛋白酶在酸性环境下极不稳定，在弱碱环境（ｐＨ８．５－９．５）中活性最高。

PURIFICATION AND PARTIAL CHARACTERIZATION OF A GUT TRYPSIN-LIKE PROTEASE FROM LARVAE OF FLESH FLY, BOETTCHERISCA PEREGRINA (DIPTERA: SARCOPHAGAE)

A 16kD protease was purified from the gut extract of larvae of Boettcherisca peregrina, after ammonium sulfate precipitation, DEAE-Sephadex A-25 ion-exchange chromatography and SBBI-Sepharose 4B affinity chromatography. The results of substrate and inhibitor specificity indicated that the protease behaved as a trypsin-like protease. It possesses high activity against non-specific substrate casein and Hide powder azure, and against trypsin-specific substrates Bz-Phe-Val-Arg NA, Bz-Pro--Phe-Arg NA and BzVal-Gly-Arg NA. It can be strongly inhibited by PMSF, phenymethysulfonyl fluoride (serine protease inhibitor), SBBI, soybean Bowman-Birk inhibitor and Leupeptin (trypsin-specific inhibitor). Activity of this protease was found to be maximal at the alkaline range of PH 8. 5- 9.5.