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目的：采用上海医科大学（ＳＭＵ）医学螨类研究室培养的粉尘螨（Ｄｅｒｍａｔｏｐｈａｇｏｉｄｅｓｆａｒｉｎａｅ）提纯粉尘螨４类变应原（Ｄｅｒｆ４），并对其作淀粉酶活性分析。方法：首次运用２０％－５０％饱和硫酸铵分级沉淀、ＳｅｐｈａｄｅｘＧ－１５０与Ｇ－５０凝胶层析、聚丙烯酰胺凝胶制备电泳（ＰＡＧＥ）等方法相结合，系列分离纯化粉尘螨代谢培养基（Ｄｆ）中的Ｄｅｒｆ４。提纯过程中每步都作蛋白质含量测定，并作淀粉酶活性分析。对纯化的Ｄｅｒｆ４进行理化性质的鉴定。结果：（１）从Ｄｆ经系列分离纯化粉尘螨代谢培养基获得ＳＭＵ－Ｄｅｒｆ４，最终得率为０．９８％；（２）淀粉酶的比活性从０．０９Ｕ／ｍｇ增加至４．６１Ｕ／ｍｇ，淀粉酶的纯化倍数为５１．２倍，得率为４３．１％；（３）在ＳＤＳ－ＰＡＧＥ电泳上只显示一条蛋白质条带，分子量ＭＷ５８ｋＤａ；（４）在等电聚焦电泳（ＩＥＦ）上显示多个蛋白质条带，呈异质性，等电点ｐＩ５．１８—７．２０。结论：ＳＭＵ－Ｄｅｒｆ４有淀粉酶活性，其理化性状符合Ｄｅｒｆ４的特性。改用分离一般蛋白质常用的方法提取Ｄｅｒｆ４得率较国外报道的糖原－淀粉酶乙醇沉淀法为高。
OBJECTIVE: To purify Derfen 4 gene of Dermatophagoides farinae by Dermatophagoides farinae collected from the Laboratory of Medical Mites, Shanghai Medical University (SMU), and analyze its amylase activity. Methods: For the first time, 20% -50% saturated ammonium sulfate fractionation and sedimentation were used. Sephadex G-150 was coupled with G-50 gel filtration and polyacrylamide gel electrophoresis (PAGE) (Df) in Derf4. Each step in the purification process for the determination of protein content, and amylase activity analysis. The purified Derf4 physical and chemical properties of the identification. Results: (1) The final yield of SMU-Derf4 was 0.98% from the Df purified Dermatophagoides farinae metabolism medium; (2) The specific activity of amylase increased from 0.09U / mg to 4.61U / mg, the purification fold of amylase was 51.2 times, the yield was 43.1%; (3) Only one protein band was displayed on SDS-PAGE electrophoresis, MW58kDa; (4) In isoelectric focusing electrophoresis ) Showed multiple protein bands, showing heterogeneity, isoelectric point pI5.18-7.20. Conclusion: SMU-Derf4 has amylase activity, and its physical and chemical properties are in line with the characteristics of Derf4. Switch to the general method of separation of proteins used to extract Derf4 yield than the reported glycogen - amylase ethanol precipitation method is high.