【摘要】 为了研究棉铃虫（Ｈｅｌｉｃｏｖｅｒｐａ　ａｒｍｉｇｅｒａ） 半胱氨酸蛋白酶的底物专一性，进一步阐明该蛋白酶的性质和应用前景，从棉铃虫卵巢中纯化了该蛋白酶，用电泳方法检测了该蛋白酶对牛血红蛋白（Ｈｂ）、牛血清蛋白（ＢＳＡ）、卵黄磷蛋白（Ｖｎ）、明胶（ｇｅｌａｔｉｎ）等 ４种动物蛋白，及大豆、玉米、马铃薯、豇豆、向阳花种子及棉籽蛋白等 ６种植物蛋白的水解作用。结果显示该酶对４种动物蛋白及６种植物蛋白都有明显水解活性。用吸光度测定法测定了棉铃虫半胱氨酸蛋白酶对牛血红蛋白、牛血清蛋白、卵黄磷蛋白、明胶等４种底物的米氏常数（Ｋｍ） 值。结果显示棉铃虫半胱氨酸蛋白酶对牛血红蛋白和卵黄磷蛋白的水解产物的吸光度值较高，而对牛血清蛋白和明胶的水解产物的吸光度值较低。测得该蛋白酶对牛血红蛋白、牛血清蛋白、卵黄磷蛋白、明胶的Ｋｍ值分别为 １０、０．９１、０．０８μｍｏｌ／Ｌ和２５０ｍｇ／Ｌ，其中对卵黄磷蛋白的Ｋｍ值最小，说明棉铃虫半胱氨酸蛋白酶与卵黄磷蛋白的亲和力最大，即卵黄磷蛋白是棉铃虫半胱氨酸蛋白酶的最适底物。同时用电泳方法检测了该蛋白酶对粗提的棉铃虫卵黄磷蛋白的水解作用，结果显示该酶对其有明显水解活性，由此推测该酶可能参与棉铃虫更多还原

【Abstract】 Eggs of the cotton boll worm, Helicoverpa armigera, contain a high level of a proteinase which is most active in acidic pH region. The proteinase has been purified from the extract of eggs and characterized to be a cysteine proteinase. To investigate the enzyme’s substrate specificity and clarify its properties and its prospect of practical uses we use SDS-PAGE electrophoresis to analyse the activity of the enzyme by hydrolyzing some proteins. The substrates are four animal proteins, Hb, BSA, Vn (Helicoverpa armigera) and gelatin; and six plant proteins, soybean protein, potato tubers protein, cowpea protein, maize protein, sunflower seeds protein, cotton seeds protein. The result implies that the encyme can actively hydrolyze these proteins. Then we use Lowry method to study the Km of the enzyme to Hb, BSA, Vn (Antherea pernyi) and gelatin. It shows that the absorption of the proteinase at OD750 towards Hb and Vn are higher than those of BSA and gelatin, which might because of the composition.ofthe amino acids in proteins. Km of Hb, BSA, Vn (Antherea pernyi) and gelatin are l0,0.9l,0.08 μmol/L and 250 mg/L, respectively. Vn is found to be hydrolyzed by the cysteine proteinase with higher specificity than other three substrates. The result of SDS-PAGE electrophoresis shows that Vn from Heli- coverpa armigera eggs can be hydrolyzed by the enzyme effectively, which suggests that the enzyme might play a role in protein de- gradation during embryonic development of Helicoverpa armigera eggs.更多还原