(15)N骨干ferricytochrome动力学b(562):比较减少蛋白质和R98C变体。
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Assfalg M, Banci L,贝尔蒂尼我Ciofi-Baffoni年代,巴克PD
(15)N骨干ferricytochrome动力学b(562):比较减少蛋白质和R98C变体。
生物化学。2001年10月30日,40 (43):12761 - 71。
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11669612 (在PubMed]
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的骨干动态ferricytochrome b(562),从大肠杆菌四螺旋束蛋白,研究了核磁共振光谱学。引入c -型硫醚的后果之间的联系,减少亚铁血红素和蛋白质细胞色素也被分析。(15)N放松利率R(1)和(2)和(1)H ~ (15) N不测量质子拉莫尔频率的500和600 MHz的氧化和减少蛋白质以及氧化R98C变体。在后一种蛋白,一个“人造”硫醚共价键之间引入了血红素组和蛋白质框架[Arnesano F。Banci, L。贝尔蒂尼,我。、Ciofi-Baffoni年代。拉姆利德Woodyear, T。约翰逊,c . M。巴克,p . d .(2000)生物化学39岁,1499 - 1514]。(15)N弛豫数据分析ModelFree协议,和流动参数对皮秒纳秒时间尺度比较三种。三种形式,而坚硬的作为一个整体,广义订单参数值平均为0.87 + / - 0.08(氧化细胞色素b(562)), 0.84 + / - 0.07(减少细胞色素b(562))和0.85 + / - 0.07(氧化R98C细胞色素b(562)),为每个系统表明类似的流动性。 Lower order parameters (S(2)) are found for residues belonging to loops 1 and 2. Higher mobility, as indicated by lower order parameters, is found for heme binding helices alpha 1 and alpha 4 in the R98C variant with respect to the wild-type protein. The analysis requires a relatively long rotational correlation time (tau(m) = 9.6 ns) whose value is accounted for on the basis of the anisotropy of the molecular shape and the high phosphate concentration needed to ensure the occurrence of monomer species. A parallel study of motions in the millisecond to microsecond time scale has also been performed on oxidized wild-type and R98C cytochrome b(562). In a CPMG experiment, decay rates were analyzed in the presence of spin-echo pulse trains of variable spacing. The dynamic behavior on this time scale is similar to that observed on the sub-nanosecond time scale, showing an increased mobility in the residues connected to the heme ligands in the R98C variant. It appears that the increased protein stability of the variant, established previously, is not correlated with an increase in rigidity.