An effective method for the isolation of plasma membrane ( PM) from rice, Oryza sativa, seedlings was established using aqueous two-phase system which was composed of Dextran T 500 and PEG 3350. The effect of the concentration of the polymer on partition of PM in polymer system was studied. Phase separation was carried out in a series of two-phase systems containing 6. 1% -6. 5% (w) of each polymer dissolved in phase buffer. The result indicated that the most effective phase partition system which consisted of 6. 3%/6. 3% (w) PEG 3350/Dextran T 500 in 0. 25 mol/L sucrose, 5 mmol/L potassium phosphate and 3 mmol/L KC1 ( pH 7. 8) was suitable for the isolation of PM from rice. The electron micrograph stained with uranyl actate-lead citrate stain and marker enzyme activities analysis proved that the isolated PM had obtained high purity (93. 5% ) and right-side out sealed vesicles. Purified PM proteins were also obtained from crude PM in good yield (2. 73% ). To improve the solubilization of hydro-phobic PM proteins and dissociate protein complexes, PM proteins were treated by an optimized rehydra-tion buffer including new zwitteronic detergents, just as ASB-14 and CHAPS. 1-D SDS-PAGE of purified PM proteins showed more band numbers and well-proportioned bands intensity than that of crude PM. PM proteins were also separated by IEF/SDS-PAGE. 579 ±17 well-resolved proteins with a much clearerbackground were obtained, which also showed good reproducibility among three independent experiments. The result above showed that the method to purify PM proteins using the aqueous two-phase partition system could be suitable for high-throughput PM proteomic analysis, such as SDS-PAGE combined with HPLC-ESI-MS/MS and 2-DE analysis.%采用双水相分配法和离心法对水稻叶片的细胞质膜进行了纯化.选用聚合物Dextran T 500/ PEG 3350质量分数分别为6.1％、6.2％、6.3％、6.4％、6.5％的双水相体系,对3次分配后的细胞质膜纯化效果进行了研究,并进行了细胞质膜标志酶H+ -ATPase的活性测定、柠檬酸铅-醋酸铀双染色及电镜检测.结果表明:聚合物质量分数为6.3％的双水相体系可以获得高纯度的质膜微囊,且随分配次数的增加,可以有效减少其他内膜的污染,其质膜标志酶VO3-4 -ATPase的相对活性高达93.5％.粗质膜经过3次两相分配后的蛋白质产率为2.73％.非离子型去垢剂Brij 58对质膜H+-ATPase的活性变化影响结果表明,纯化的质膜微囊封闭性较好,主要为正向型质膜微囊.质膜蛋白质经增溶缓冲液溶解及1-D SDS-PAGE的结果表明,纯化后的质膜有效减少了特定蛋白质条带的丰度,使蛋白质条带的分布更为均匀.双向电泳结果表明,纯化后的质膜双向电脉图谱具有低背景、高分辨率和重复性的优点,为进一步的水稻质膜蛋白质组研究提供了可靠的试验材料.
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