Rodríguez-Maciá Patricia, Reijerse Edward, Lubitz Wolfgang, Birrell James A, Rüdiger Olaf
Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.
J Phys Chem Lett. 2017 Aug 17;8(16):3834-3839. doi: 10.1021/acs.jpclett.7b01608. Epub 2017 Aug 4.
[FeFe] hydrogenases are extremely active and efficient H-converting biocatalysts. Their active site comprises a unique [2Fe] subcluster bonded to a canonical [4Fe-4S] cluster. The [2Fe] subsite can be introduced into hydrogenases lacking an assembled H-cluster through incubation with a synthesized [2Fe] precursor, which initially produces the CO-inhibited state of the enzyme. We present FTIR spectroelectrochemical studies on the CO-inhibited state of the [FeFe] hydrogenase from Desulfovibrio desulfuricans, DdHydAB. At very negative potentials, disassembly of the H-cluster and dissociation of the [2Fe] subcluster is observed. Subsequently raising the potential allows cofactor rebinding and H-cluster reassembly. This demonstrates how the stability of the [2Fe]-[4Fe-4S] intercluster bond depends on the applied potential and the presence of an inhibiting CO ligand on the [2Fe] subcluster. These results provide insight into the mechanisms of CO inhibition and H-cluster assembly in [FeFe] hydrogenases. A fundamental understanding of these properties will provide clues for designing better H-converting catalysts.
[铁铁]氢化酶是极具活性且高效的氢转化生物催化剂。它们的活性位点包含一个独特的与标准[4铁-4硫]簇相连的[2铁]亚簇。通过与合成的[2铁]前体孵育，可将[2铁]亚位点引入缺乏组装好的H簇的氢化酶中，这最初会产生该酶的一氧化碳抑制状态。我们展示了对脱硫脱硫弧菌（DdHydAB）的[铁铁]氢化酶的一氧化碳抑制状态的傅里叶变换红外光谱电化学研究。在非常负的电位下，观察到H簇的拆解和[2铁]亚簇的解离。随后提高电位会使辅因子重新结合并使H簇重新组装。这证明了[2铁]-[4铁-4硫]簇间键的稳定性如何取决于所施加的电位以及[2铁]亚簇上抑制性一氧化碳配体的存在。这些结果为深入了解[铁铁]氢化酶中一氧化碳抑制和H簇组装的机制提供了线索。对这些特性的基本理解将为设计更好的氢转化催化剂提供线索。
