Role of Enzymes in the Biosynthesis of Hydrogenase H cluster

氢化酶是一种潜在的环境友好的生物能源，使用复杂的辅因子催化质子可逆还原形成氢气。最活跃的亚类[FeFe]-氢化酶依赖于金属辅因子H簇，其由两个铁亚簇（[2Fe]H）桥接到经典的立方烷簇（[4Fe-4S]H）组成。配位到二铁子簇的配体包括氮杂二硫醇盐、三个一氧化碳和两个氰化物。为了组装这种复杂的辅因子，需要三种成熟酶HydG、HydE和HydF。的双原子配体的生物合成收益的一个不寻常的碎片化机制，并结合光谱分析的结构研究已经开始提供深入了解HydG介导的组装的[2Fe]H亚簇前体。一个有机金属中间体CysFe（CO）2CN，被认为是HydG的产物。它的功能是作为一个合成子，用于随后的H-簇组装。研究将侧重于理解H簇组装的化学机制。结构研究将集中在理解底物结合到HydG的活性位点。光谱和生物化学研究将集中在表征HydG产生的有机金属中间体，并阐明氢化酶激活所需的后续步骤

Hydrogenases are a potential source of environmentally benign bioenergy, using complex cofactors to catalyze the reversible reduction of protons to form hydrogen. The most active subclass, the [FeFe]-hydrogenases, is dependent on a metallocofactor, the H cluster, that consists of a two iron subcluster ([2Fe]H) bridging to a classical cubane cluster ([4Fe-4S]H). The ligands coordinating to the diiron subcluster include an azadithiolate, three carbon monoxides, and two cyanides. To assemble this complex cofactor, three maturase enzymes, HydG, HydE and HydF are required. The biosynthesis of the diatomic ligands proceeds by an unusual fragmentation mechanism, and structural studies in combination with spectroscopic analysis have started to provide insights into the HydG mediated assembly of a [2Fe]H subcluster precursor. An organometallic intermediate CysFe(CO)2CN, is proposed as the product of HydG. It functions as a synthon for subsequent H-cluster assembly. Studies will focus on understanding the chemical mechanisms of H cluster assembly. Structural studies will concentrate on understanding substrate binding to the active site of HydG. Spectroscopic and biochemical studies will focus on characterising the organometallic intermediate generated by HydG and elucidating the subsequent steps required for hydrogenase activation