【摘要】 从鹅绒藤 (CynanchumchineseR .Br.)茎干乳汁中用凝胶层析 ,离子交换层析纯化蛋白酶。经SDS PAGE、IEF鉴定 ,为均一条带。分子质量 18ku ;pI 6.7;作用最适pH 7.0 ,最适温度范围 60～ 80℃。对HbA β链水解的Km值为 1.5 9× 10 -6mol L。巯基酶抑制剂、保护剂实验提示该酶为巯基蛋白酶。用五肽胃泌素做底物 ,通过分配层析分离并用DABITC PITC双偶合法对肽斑片段测序的结果表明 ,该蛋白酶的水解位点特异性较低。结论 :该酶是一种活性较强的巯基蛋白酶更多还原

【Abstract】 To isolate and purify a proteinase from Cynanchum c hi nese R.Br. latex, the latex was purified by gel filtration and chromatography o n DEAE-cellulose DE-32. Results showed that the proteinase was a monomeric pro tein with an approximate molecular mass of 18ku. The isoelectric point was 6.7,o ptimum temperature range and pH were 60～80℃ and 7.0, respectively. The enzyme activity was inhibit ed by iodoacetate ,protected by DTT. Mapping of the specificity sites of protei nase indicated that the enzyme has broad substrate specificity. The proteinase i s a cysteinase with strong activity.更多还原