...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Characterization of pheophytin ground states in Rhodobacter sphaeroides R26 photosynthetic reaction centers from multispin pheophytin enrichment and 2-D 13C MAS NMR dipolar correlation spectroscopy
【24h】

Characterization of pheophytin ground states in Rhodobacter sphaeroides R26 photosynthetic reaction centers from multispin pheophytin enrichment and 2-D 13C MAS NMR dipolar correlation spectroscopy

机译：多旋脱镁叶绿素富集和2-D 13C MAS NMR偶极相关光谱法表征球形红球菌R26光合反应中心中脱镁叶绿素的基态

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The electronic ground states of pheophytin cofactors potentially involved in symmetry breaking between the A and B branch for electron transport in the bacterial photosynthetic reaction center have been investigated through a characterization of the electron densities at individual atomic positions of pheophytin a from 13C chemical shift data. A new experimental approach involving multispin 13C labeling and 2-D NMR is presented. Bacterial photosynthetic reaction centers of Rhodobacter sphaeroides R26 were reconstituted with uniformly 13C biosynthetically labeled (plant) Pheo a in the two pheophytin binding sites. From the multispin labeled samples 1-D and 2-D solid-state 13C magic angle spinning NMR spectra could be obtained and used to characterize the pheophytin a ground state in the Rb. sphaeroides R26 RCs, i.e., without a necessity for time-consuming selective labeling strategies involving organic synthesis. From the 2-D solid state 13C-13C correlation spectra collected with spinning speeds of 8 and 10 kHz, with mixing times of 1 and 0.8 ms, many 13C resonances of the [U-13C]Pheo a molecules reconstituted in the RCs could be assigned in a single set of experiments. Parts of the pheophytins interacting with the protein, at the level of 13C shifts modified by binding, could be identified. Small reconstitution shifts are detected for the 17(2) side chain of ring IV. In contrast, there is no evidence for electrostatic differences between the two Pheo a, for instance, due to a possibly strong selective electrostatic interaction with Glu L104 on the active branch. The protonation states appear the same, and the NMR suggests a strong overall similarity between the ground states of the two Pheo a, which is of interest in view of the asymmetry of the electron transfer.
机译：通过根据13C化学位移数据表征脱镁叶绿素a各个原子位置的电子密度，研究了潜在与脱镁叶绿素辅因子在细菌光合作用反应中心中进行电子传输的对称断裂的电子基态的电子基态。提出了一种新的实验方法，涉及多旋13C标记和2-D NMR。球形球形红细菌R26的细菌光合作用反应中心在两个脱镁叶绿素结合位点用统一的13C生物合成标记（植物）Pheo a重建。从多旋转标记的样品中，可以获得1-D和2-D固态13C幻角旋转NMR光谱，并将其用于表征脱镁叶绿素在Rb中的基态。球菌R26 RC，即不需要涉及有机合成的费时的选择性标记策略。从以8和10 kHz的旋转速度收集的2D固态13C-13C相关光谱中，混合时间为1和0.8 ms，[U-13C] Pheo a分子在RC中重构的许多13C共振可能是在一组实验中分配。与结合蛋白相互作用的脱镁叶绿素的部分，在通过结合修饰的13C转变水平上可以被鉴定。小的重组移位检测到环IV的17（2）侧链。相反，没有证据表明两个Pheo a之间存在静电差异，例如，由于与活性分支上的Glu L104可能存在强烈的选择性静电相互作用。质子化态看起来是相同的，并且NMR表明两个Pheo a的基态之间具有很强的整体相似性，考虑到电子转移的不对称性，这是有意义的。

著录项

相似文献

  • 外文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号