柞蚕卵组织蛋白酶B纯化及性质

昆虫卵内蛋白酶在胚胎发育中水解卵黄蛋白，为胚胎发育提供氨基酸，昆虫中已报道过几类卵蛋白酶，如家蚕中半胱氨酸蛋白酶和丝氨酸蛋白酶等。但是，目前尚不清楚这些蛋白酶是否存在于其他鳞翅目昆虫。了解这些蛋白酶的作用机理可以为我们提供害虫防治的新方法。并且，由于蛋白水解在许多生理过程中具有重要作用，如蛋白质的成熟和转运、受精、萌芽、肿瘤转移和其他形态发生等。因此，阐明这些蛋白酶的生物功能具有重要意义。由于（ｉ蚕卵粒大产卵量也很大，因此被选作研究鳞翅目昆虫卵蛋白酶的材料，我们希望通过对数种昆虫卵内蛋白酶的研究、找出卵黄蛋白水解的一般规律。在我们前一篇文章中报道了（ｉ蚕组织蛋白酶Ｂ的鉴定，该蛋白酶属于半胱氨酸蛋白酶类的组织蛋或最适ｐＨ为３．５，可被Ｅ－６４抑制。本文报道蛋白酶的纯化和性质。经过５步纯化过程，从（ｉ蚕卵母细胞中纯化出组织蛋白酶Ｂ，用ＳＤＳ聚丙烯酰胺凝胶电泳测得蛋白酶的亚基分子量在４７ｋＤａ左右。纯化的蛋白酶活性可被Ｅ－６４和Ｌｅｕｐｅｐｔｉｎ抑制。因此，该蛋白酶属于半胱氨酸蛋白酶。天冬氨酸蛋白酶特异性抑制剂ｐｅｐｓｔａｔｉｎ不抑制其活性。其活性可被ＤＦＰ和ＰＭＳＦ部分抑制。这两种抑制剂通常抑制丝氨酸蛋白酶活性

Purification and Characterization of a Cathepsin B-Like Proteinase from Eggs of Antheraea Pernyi

A cathepsin B-like proteinase was purified from eggs of Antheraea pernyi by 5 steps of purification. The molecular mass of the proteinase are estimated to be 47 kDa by using SDS-polyacrylamide gel electro-phoresis. The activity of the purified proteinase were strongly inhibited by E-64 and Leupeptin. The optimum pH is 3.5 as determined by using the bovine hemo-globin as substrate. The activity and quantity of the proteinase during embryo development were studied. The results suggested that the proteolytic activities during embryo development at least partially came from this proteinase.