• 主题
高级搜索  >
历史搜索 清空历史
首页> 美国卫生研究院文献>other >Geometries and Electronic Structures of Cyanide Adducts of the Non-Heme Iron Active Site of Superoxide Reductases: Vibrational and ENDOR Studies
【2h】

Geometries and Electronic Structures of Cyanide Adducts of the Non-Heme Iron Active Site of Superoxide Reductases: Vibrational and ENDOR Studies

机译：超血红素还原酶非血红素铁活性位点氰化物加合物的几何结构和电子结构：振动和ENDOR研究

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务，本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文，但由于OA文献来源多样且变更频繁，仍可能出现获取不到、文献不完整或与标题不符等情况，如果获取不到我们将提供退款服务。请知悉。
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We have added cyanide to oxidized 1Fe and 2Fe superoxide reductase (SOR) as a surrogate for the putative ferric-(hydro)peroxo intermediate in the reaction of the enzymes with superoxide, and have used vibrational and ENDOR spectroscopies to study the properties of the active-site paramagnetic iron center. Addition of cyanide changes the active-site iron center in oxidized SOR from rhombic high-spin ferric (S = 5/2) to axial-like low-spin ferric (S = 1/2). Low-temperature resonance Raman and ENDOR data show that the bound cyanide adopts three distinct conformations in Fe(III)-CN SOR. On the basis of 13CN, C15N, and 13C15N isotope shifts of the Fe–CN stretching/Fe–C–N bending modes, resonance Raman studies of 1Fe-SOR indicate one near-linear conformation (Fe–C–N angle ∼175°) and two distinct bent conformations (Fe–C–N angles < 140°). FTIR studies of 1Fe-SOR at ambient temperatures reveals three bound C–N stretching frequencies in the oxidized (ferric) state and one in the reduced (ferrous) state indicating that the conformational heterogeneity in cyanide binding is a characteristic of the ferric state and is not caused by freezing-in of conformational substates at low temperature. 13C-ENDOR spectra for the 13CN-bound ferric active sites in both 1Fe- and 2Fe-SORs also show three well-resolved Fe–C–N conformations. Analysis of the 13C hyperfine tensors for the three substates of the 2Fe-SOR within a simple heuristic model for the Fe-C bonding gives values for the Fe–C–N angles in the three substates of ca. 123° (C3), 133° (C2), taking a reference value from vibrational studies of 175° (C1 species). Resonance Raman and ENDOR studies of SOR variants, in which the conserved glutamate and lysine residues in a flexible loop above the substrate binding pocket have been individually replaced by alanine, indicate that the side chains of these two residues are not involved in direct interaction with bound cyanide. The implications of these results for understanding the mechanism of SOR are discussed.
机译：我们在氧化的1Fe和2Fe超氧化物还原酶（SOR）中添加了氰化物，作为酶与超氧化物反应中推定的铁-（氢）过氧中间体的替代物，并使用振动和ENDOR光谱学研究了活性物质的性能。现场顺磁性铁心。氰化物的添加将氧化SOR中的活性位铁中心从菱形高自旋铁（S = 5/2）变为轴状低自旋铁（S = 1/2）。低温共振拉曼和ENDOR数据表明，结合的氰化物在Fe（III）-CN SOR中采用三个不同的构象。根据Fe–的 13 CN，C 15 N和 13 C 15 N同位素位移CN拉伸/ Fe–C–N弯曲模式，1Fe-SOR的共振拉曼研究表明一种近线性构型（Fe–C–N角约为175°）和两种不同的弯曲构型（Fe–C–N角<140°） ）。在环境温度下对1Fe-SOR的FTIR研究表明，在氧化（铁）态中有3个键合的C–N拉伸频率，在还原（亚铁）态中有1个键合频率，表明氰化物结合中的构象异质性是铁态的特征，并且并非由低温构象亚状态的冻结所引起。在1Fe-SOR和2Fe-SOR中 13 CN结合的三价铁活性位点的 13 C-ENDOR光谱也显示出三个分辨良好的Fe–C–N构象。在简单的启发式Fe-C键合模型中，对2Fe-SOR的三个子状态的 13 C超精细张量进行分析，得出ca的三个子状态下的Fe–C–N角值。 123°（C3），133°（C2），取自175°（C1种）的振动研究的参考值。 SOR变体的共振拉曼和ENDOR研究表明，底物结合口袋上方柔性环中的保守谷氨酸和赖氨酸残基已分别被丙氨酸取代，表明这两个残基的侧链不参与与结合分子的直接相互作用。氰化物。讨论了这些结果对于理解SOR机制的意义。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
代理获取

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