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首页> 外文期刊>Biochemistry >Electron Paramagnetic Resonance Characterization of the Triheme Cytochrome from &ITGeobacter sulfurreducens&IT
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Electron Paramagnetic Resonance Characterization of the Triheme Cytochrome from &ITGeobacter sulfurreducens&IT

机译：来自＆异常硫化琥珀素的Trieme细胞色素的电子顺磁共振特征

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摘要

Periplasmic cytochrome A (PpcA) is a representative of a broad class of multiheme cytochromes functioning as protein "nanowires" for storage and extracellular transfer of multiple electrons in the delta-proteobacterium Geobacter sulfurreducens. PpcA contains three bis-His coordinated hemes held in, a spatial arrangement that is highly conserved among the multiheme cytochromes c(3) and c(7) families, carries low potential hemes, and is notable for having one of the lowest number of amino acids utilized to maintain a characteristic protein fold and site-specific heme function. Low temperature X-band electron paramagnetic resonance (EPR) spectroscopy has been used to characterize the electronic configuration of the Fe(III) and the ligation mode for each heme. The three sets of EPR signals are assigned to individual hemes in the three-dimensional crystal structure. The relative energy levels of the Fe(III) 3d orbitals for individual hemes were estimated from the principal g-values. The observed g-tensor anisotropy was used as a probe of electronic structure of each heme, and differences were determined by specifics of axial ligation. To ensure unambiguous assignment of highly anisotropic low-spin (HALS) signal to individual hemes, EPR analyses of iron atom electronic configurations have been supplemented with investigation of porphyrin macro cycles by one-dimensional H-1 NMR chemical shift patterns for the methyl substituents. Within optimized geometry of hemes in PpcA, the magnetic interactions between hemes were found to be minimal, similar to the c(3) family of tetraheme cytochromes.
机译：周质细胞色素A（PPCA）是一种具有作为蛋白质“纳米线”的广泛多血脂细胞变色剂的代表，用于蛋白质“纳米线”，用于储存和细胞外，在Δ-促菌根硫化琥珀酸盐中的多个电子。 PPCA含有三个双级的协调血液，在多血症细胞色素C（3）和C（7）家族中具有高度保守的空间布置，携带低潜在的血液，并且对于具有最低数量的氨基是值得注意的用于维持特征蛋白折叠和特异性血红素功能的酸。低温X波段电子顺磁共振（EPR）光谱已经用于表征Fe（III）的电子结构和每个血红素的连接模式。三组EPR信号被分配给三维晶体结构中的各个血液。从主G值估计单个血液的Fe（III）3D轨道的相对能量水平。观察到的G-张量各向异性被用作每个血红素的电子结构的探针，并且通过轴连接的细节确定差异。为了确保对单个血液的高位各向异性低旋转（HALS）信号的明确分配，通过对甲基取代基的一维H-1 NMR化学变换模式对卟啉宏循环进行了补充，对铁原子电子构造的EPR分析已经补充。在PPCA中优化的几何形状内，发现血液之间的磁性相互作用最小，类似于C（3）四种细胞变色剂的C（3）。

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  • 来源
    《Biochemistry》 |2018年第11期|共11页
  • 作者

    Ponomarenko Nina; Niklas Jens; Pokkuluri P. Raj; Poluektov Oleg; Tiede David M.;

  • 作者单位

    Argonne Natl Lab Chem Sci &

    Engn Div 9700 South Cass Ave Argonne IL 60439 USA;

    Argonne Natl Lab Chem Sci &

    Engn Div 9700 South Cass Ave Argonne IL 60439 USA;

    Argonne Natl Lab Biosci Div 9700 South Cass Ave Argonne IL 60439 USA;

    Argonne Natl Lab Chem Sci &

    Engn Div 9700 South Cass Ave Argonne IL 60439 USA;

    Argonne Natl Lab Chem Sci &

    Engn Div 9700 South Cass Ave Argonne IL 60439 USA;

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  • 正文语种 eng
  • 中图分类 生物化学;
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