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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface
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Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface

机译：细胞色素c中的血红素-蛋白质振动偶合提供了将血红素铁与蛋白质表面连接起来的动态链接

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摘要

The active site of cytochrome c (Cyt c) consists of a heme cova-lently linked to a pentapeptide segment (Cys-X-X-Cys-His), which provides a link between the heme and the protein surface, where the redox partners of Cyt c bind. To elucidate the vibrational properties of heme c, nuclear resonance vibrational spectroscopy (NRVS) measurements were performed on ~(57)Fe-labeled ferric Hydrogenobacter thermophilus cytochrome c_(552), including 13Cs-heme-, ~(13)C_5~(15)N-Met-, and ~(13)C~(15)N-polypeptide (ppHabeled samples, revealing heme-based vibrational modes in the 200- to 450-cm~(-1) spectral region. Simulations of the NRVS spectra of H. thermophilus cytochrome c_(552) allowed for a complete assignment of the Fe vibrational spectrum of the protein-bound heme, as well as the quantitative determination of the amount of mixing between local heme vibrations and pp modes from the Cys-X-X-Cys-His motif. These results provide the basis to propose that heme-pp vibrational dynamic couplings play a role in electron transfer (ET) by coupling vibrations of the heme directly to vibrations of the pp at the protein-protein interface. This could allow for the direct transduction of the thermal (vibrational) energy from the protein surface to the heme that is released on protein/protein complex formation, or it could modulate the heme vibrations in the protein/protein complex to minimize reorganization energy. Both mechanisms lower energy barriers for ET. Notably, the conformation of the distal Met side chain is fine-tuned in the protein to localize heme-pp mixed vibrations within the 250-to 400-cm~(-1) spectral region. These findings point to a particular orientation of the distal Met that maximizes ET.
机译：细胞色素c（Cyt c）的活性位点由与五肽片段（Cys-XX-Cys-His）紧密连接的血红素组成，该血红素提供了血红素与蛋白质表面之间的连接，Cyt的氧化还原伙伴c绑定。为了阐明血红素c的振动特性，对〜（57）Fe标记的铁嗜热氢杆菌细胞色素c_（552）进行了核磁共振波谱（NRVS）测量，包括13Cs-血红素-，〜（13）C_5〜（15） N-Met-和〜（13）C〜（15）N-多肽（ppHabeled样品，揭示了在200-450 cm〜（-1）光谱范围内基于血红素的振动模式。NRVS光谱的模拟嗜热链球菌细胞色素c_（552）的合成可完全确定结合蛋白的血红素的Fe振动光谱，并定量确定Cys-XX-的局部血红素振动与pp模式之间的混合量Cys-His基序，这些结果为提出血红素-pp振动动态偶联通过将血红素的振动直接与蛋白质-蛋白质界面上的pp振动耦合而在电子传递（ET）中发挥作用提供了依据。用于直接传导来自pr的热（振动）能量血红蛋白表面上的血红素在蛋白质/蛋白质复合物形成时释放，或者它可以调节蛋白质/蛋白质复合物中血红素的振动，以最大程度地减少重组能量。两种机制都降低了ET的能垒。值得注意的是，在蛋白质中微调了远端Met侧链的构象，以将血红素-pp混合振动定位在250至400cm〜（-1）的光谱区域内。这些发现指向远端ET的最大化ET的特定方向。

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    Mary Grace I. Galinato; Jesse G. Kleingardner; Sarah E. J. Bowman; E. Ercan Alp; Jiyong Zhao; Kara L. Bren; Nicolai Lehnert;

  • 作者单位

    Department of Chemistry, University of Michigan, Ann Arbor, Ml 48109,Department of Chemistry, School of Science, Penn State Erie, The Behrend College, Erie, PA 16563;

    Department of Chemistry, University of Rochester, Rochester, NY 14627;

    Department of Chemistry, University of Rochester, Rochester, NY 14627,Department of Chemistry and Biochemistry, University of Minnesota at Duluth, Duluth, MN 55812;

    Advanced Photon Source/Experimental Facilities Division, Argonne National Laboratory, Argonne, IL 60439;

    Advanced Photon Source/Experimental Facilities Division, Argonne National Laboratory, Argonne, IL 60439;

    Department of Chemistry, University of Rochester, Rochester, NY 14627;

    Department of Chemistry, University of Michigan, Ann Arbor, Ml 48109;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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