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棕尾别麻蝇幼虫肠液经ＳＤＳ－ＰＡＧＥ后，Ｘ光片显影，呈现两条蛋白酶活性带．ＩＥＦ后，两条蛋白酶活性带的等电点分别为ｐＨ７．７和６．８．麻蝇幼虫肠液经５５％～７５％硫酸铵沉淀，以及连续两次制备等电聚焦，分离纯化出等电点约为ｐＨ７．７，分子量约为３５ｋＤ的蛋白酶ＢＧＰ．该酶能分解酪蛋白和类胰蛋白酶专一底物Ｂｚ－Ｐｈｅ－Ｖａｌ－ＡｒｇＮＡ，不能分解弹性蛋白酶专一底物ｅｌａｓｔｉｎ－ＣｏｎｇｏＲｅｄ和类胰凝乳蛋白酶专一底物Ｓｕｃ（Ａｌａ）２Ｐｒｏ－ＰｈｅＮＡ．ＳＢＢＩ，Ｌｅｕｐｅｐｔｉｎ和ＰＭＳＦ能强烈抑制其活性．专一底物和抑制剂的结果表明，ＢＧＰ是一种类胰蛋白酶．其最适反应温度为５０℃，最适作用ｐＨ为８．５．不耐高温，５０℃保温３０ｍｉｎ活性急剧下降．Ｈｇ２＋，Ｚｎ２＋和Ｃｕ２＋能抑制酶活性．Ｃａ２＋，Ｍｇ２＋对酶无激活作用，ＥＤＴＡ无抑制作用．
After the SDS-PAGE, the intestinal juice of C. septempunctata larvae was visualized with two protease active bands. After IEF, the isoelectric points of the two protease bands were pH7.7 and 6.8, respectively. The saprophytic larval intestinal juice was precipitated by 55% -75% ammonium sulfate, and twice continuously prepared by isoelectric focusing. The protease BGP with an isoelectric point of about pH7.7 and a molecular weight of about 35 kD was isolated and purified. The enzyme can break down the casein and tryptase specific substrate Bz-Phe-Val-ArgNA, can not break down elastase-specific substrate elastin-CongoRed and chymase-specific substrate Suc (Ala) 2Pro-PheNA . SBBI, Leupeptin and PMSF strongly inhibited their activity. Specific substrate and inhibitor results show that BGP is an tryptase. The optimum reaction temperature is 50 ℃, the optimum pH is 8.5. Not resistant to high temperature, 50 ℃ incubated 30min activity dropped sharply. Hg2 +, Zn2 + and Cu2 + inhibit enzyme activity. Ca2 +, Mg2 + no activity of the enzyme, EDTA no inhibitory effect.