Co-crystallization和表征的光合反应center-cytochrome c2复杂Rhodobacter sphaeroides。
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Adir N,阿克塞尔罗德HL Beroza P,艾萨克森RA, Rongey SH,冈,视野中时G
Co-crystallization和表征的光合反应center-cytochrome c2复杂Rhodobacter sphaeroides。
生物化学。1996年2月27日,35 (8):2535 - 47。
- PubMed ID
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8611557 (在PubMed]
- 文摘
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光合反应中心(RC) Rhodobacter sphaeroides和细胞色素c2 (cyt c2),其生理二次电子供体,co-crystallized。的摩尔比RC / cyt c2发现sds - page和光学co-crystals吸光度变化是4。3.5埃的x射线晶体衍射。然而,在数据采集分辨率退化。一个数据集,82.5%完成,收集4.5埃。水晶属于正方空间群P4(3) 2(1) 2,单胞尺寸的a = b = 142.7埃和c = 254.8埃。RCs的位置在单位细胞测定分子替换。类似的搜索cyt c2的这必威国际app种方法是失败的,因为小细胞色素总散射的贡献,因为它的入住率低。cyt c2位置是手动补丁的电子密度不同,毗邻的周质的表面M多肽RC的亚基。电子密度的差异是不够精确定位的cyt c2,建模及其取向是通过将暴露的边缘血红素的主要捐赠者反应中心D和静电相互作用,形成对RC和cyt c2氨基酸残基。 The RC-cyt c2 structure derived from the co-crystal data was supported by use of omit maps and structure refinement analyses. Cyt c2 reduces the photooxidized primary donor D+ in 0.9 +/- 0.1 micros in the co-crystals, which is the same as the fast electron transfer rate in vivo and in solution. This result provides strong evidence that the structure of the complex in the co-crystal is the same as in solution. Two additional methods were used to investigate the structure of the RC-cyt c2 complex: (i) Docking calculations based on interprotein electrostatic interactions identified possible binding positions of the cyt c2 on the RC. The cyt c2 position with the lowest electrostatic energy is very similar to that of the cyt c2 in the proposed co-crystal structure. (ii) Site-directed mutagenesis was used to modify two aspartic acid residues (M184 and L155) on the periplasmic surface of the RC. Cyt c2 binding affinity to these RCs and electron transfer rates to D+ in these RCs support the co-crystal structure of th RC-cyt c2 complex.