聚乙二醇修饰牛胰核糖核酸酶

Modification of Ribonuclease A by Methoxypolyethylene Glycol

采用N 羟基珀酰亚胺活化酯法活化单甲氧基聚乙二醇 ,测定了聚乙二醇 (PEG)的活化度为86 2 %。以活化的PEG对牛胰核糖核酸酶进行化学修饰 ;分析了蛋白质被修饰程度。用毛细管电泳法给出了被修饰蛋白的修饰度与修饰蛋白分布的定量结果。比较了被修饰产物对大分子底物 (酵母RNA)与小分子底物 (2’ ,3’ 环磷酸胞嘧啶 )的降解活力 ,其表观酶活力分别保留了 5 2 8%和 66 3 %。

Bovine pancreatic ribonuclease A (RNase) was modified with N-hydroxysucci n imide-activated methoxypolyethylene glycol (MPEG).The activation degree of MP EG was determined as 862%.The MPEG-RNase was analyzed by TNBS assay, SDS-PAG E an d capillary electrophoresis (CE).CE was chosen as efficient method for determi n ing the modification degree and characterizing the heterogeneity of MPEG-RNase . The apparent retained enzymatic activities of MPEG-RNase towards yeast RNA and c ytidine 2',3'-cyclic monophosphate were determined as 528% and 663%, respe cti vely.The revised enzymatic activities calculated by subtracting the proportion of residuary unmodified RNase according to CE analysis were also shown in this p aper