钉螺酚氧化酶分子质量测定

Study of the molecular weight of phenoloxidase from the Oncomelania snail

目的初步测定并分析钉螺酚氧化酶天然蛋白的分子质量及其亚基组成。方法通过匀浆、离心取得钉螺粗制酚氧化酶酶液,经盐析、透析、凝胶过滤等方法纯化酚氧化酶,并采用凝胶柱层析法和SDS-PAGE测定酚氧化酶的分子质量,测算其亚基组成。结果凝胶柱层析法初步测得钉螺酚氧化酶分子质量单位为91ku,SDS-PAGE4条主带分别位于87、40、37和33ku。结论钉螺体内酚氧化酶分子质量单位约为87～91ku,可能为单体酶或由3个分子质量介于33～40ku的亚基构成的寡聚酶。

Objective To understand the molecular weight and the subunit composition of phenoloxidase from the Oncomelania snail. Methods Crude fluid including phenoloxidase was prepared by homogenation and centrifugation and was purified by salt precipitation, dialysis and gel filtration. Purified fluid was used to detect the molecular weight of phenoloxidase by gel filtration and SDS-PAGE. Also, the suhunit composition of the enzyme was estimated. Results The molecular weight of phenoloxidase was determined to be 91 ku by gel filtration. Through SDS-PAGE, the enzyme was found to have 4 main bands： 87, 40, 37 and 33 ku. Conclusion The molecular weight of phenoloxidase from the Oncomelania snail is 87-91 ku. The enzyme may be a mono-enzyme or a polymer consisting of three different subunits, the molecular weights of which are 33-40 ku.