The bacterial histidine permease, an ABC transporter, from Salmonella typhimurium is composed of a membrane-bound complex, HisQMP2, comprising two hydrophobic subunits (HisQ and HisM), two copies of an ATP-hydrolyzing subunit, HisP, and a soluble receptor, HisJ. We describe the purification and characterization of HisQMP2 using a 6-histidines extension at the carboxy terminus of HisP [HisQMP2(his6)]. The purification is rapid and effective, giving a seven-fold purification with a yield of 85 and 98% purity. Two procedures are described differing in the detergent used (decanoylsucrose and octylglucoside, respectively) and in the presence of phospholipid. HisQMP2(his6) has ATPase and transport activities upon reconstitution into proteoliposomes (PLS). HisQMP2(his6) has a low level ATPase activity (intrinsic activity), which is stimulated to a different extent by the receptor--liganded and unliganded. Its pH optimum is 7.8-8.0, it requires a cation for activity and it displays cooperativity for ATP. The effect of various ATP analogs was analyzed. Determination of the molecular size of HisQMP2(his6) indicates that it is a monomer. The permeability properties of two kinds of reconstituted PLS preparations are described.

译文

来自鼠伤寒沙门氏菌的细菌组氨酸渗透酶 (ABC转运蛋白) 由膜结合复合物HisQMP2组成,该复合物包含两个疏水亚基 (HisQ和HisM),两个ATP水解亚基的拷贝,HisP和可溶性受体HisJ。我们描述了在HisP [HisQMP2(his6)] 的羧基末端使用6-组氨酸延伸来纯化和表征HisQMP2。纯化是快速和有效的,得到7倍纯化,产率为85和98% 纯度。描述了两种方法,它们在使用的洗涤剂 (分别是癸烷基蔗糖和辛基葡萄糖苷) 和磷脂存在下有所不同。HisQMP2(his6) 在重组为蛋白质脂质体 (PLS) 时具有atp酶和转运活性。HisQMP2(his6) 具有低水平的ATPase活性 (内在活性),其受到受体的不同程度的刺激-配体和未配体。它的最适pH为7.8-8.0,它需要活性阳离子,并且它显示出ATP的协同作用。分析了各种ATP类似物的作用。测定HisQMP2(his6) 的分子大小表明它是单体。描述了两种重构PLS制剂的渗透性。

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