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  • 标题:Tracking the route of molecular oxygen in O2-tolerant membrane-bound [NiFe] hydrogenase
  • 本地全文:下载
  • 作者:Jacqueline Kalms ; Andrea Schmidt ; Stefan Frielingsdorf
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:2018
  • 卷号:115
  • 期号:10
  • 页码:E2229-E2237
  • DOI:10.1073/pnas.1712267115
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:[NiFe] hydrogenases catalyze the reversible splitting of H2 into protons and electrons at a deeply buried active site. The catalytic center can be accessed by gas molecules through a hydrophobic tunnel network. While most [NiFe] hydrogenases are inactivated by O2, a small subgroup, including the membrane-bound [NiFe] hydrogenase (MBH) of Ralstonia eutropha , is able to overcome aerobic inactivation by catalytic reduction of O2 to water. This O2 tolerance relies on a special [4Fe3S] cluster that is capable of releasing two electrons upon O2 attack. Here, the O2 accessibility of the MBH gas tunnel network has been probed experimentally using a “soak-and-freeze” derivatization method, accompanied by protein X-ray crystallography and computational studies. This combined approach revealed several sites of O2 molecules within a hydrophobic tunnel network leading, via two tunnel entrances, to the catalytic center of MBH. The corresponding site occupancies were related to the O2 concentrations used for MBH crystal derivatization. The examination of the O2-derivatized data furthermore uncovered two unexpected structural alterations at the [4Fe3S] cluster, which might be related to the O2 tolerance of the enzyme.
  • 关键词:oxygen-tolerant [NiFe] hydrogenase ; metalloproteins ; iron–sulfur cluster ; X-ray crystallography ; crystal derivatization
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