Molecular Biomimetics, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 75120, Uppsala, Sweden.
Current Address: R&I Consultant, Home Office, Marseille, France.
J Biol Inorg Chem. 2022 Apr;27(3):345-355. doi: 10.1007/s00775-022-01928-5. Epub 2022 Mar 8.
Hydrogenases are metalloenzymes that catalyze the reversible oxidation of molecular hydrogen into protons and electrons. For this purpose, [FeFe]-hydrogenases utilize a hexanuclear iron cofactor, the H-cluster. This biologically unique cofactor provides the enzyme with outstanding catalytic activities, but it is also highly oxygen sensitive. Under in vitro conditions, oxygen stable forms of the H-cluster denoted H and H can be generated via treatment with sulfide under oxidizing conditions. Herein, we show that an H-like species forms spontaneously under intracellular conditions on a time scale of hours, concurrent with the cells ceasing H production. Addition of cysteine or sulfide during the maturation promotes the formation of this H-cluster state. Moreover, it is found that formation of the observed H-like species is influenced by both steric factors and proton transfer, underscoring the importance of outer coordination sphere effects on H-cluster reactivity.
氢化酶是一类金属酶，能够催化氢气可逆氧化为质子和电子。为此，[FeFe]-氢化酶利用一个六核铁辅因子，即 H 簇来实现这一过程。这种独特的生物辅因子赋予了酶极高的催化活性，但同时也使其对氧气非常敏感。在体外条件下，通过在氧化条件下用硫化物处理，可以生成氧稳定的 H 簇形式，即 H 和 H。在此，我们发现细胞停止产生 H 时，一种类似 H 的物种会在数小时内自发形成于细胞内环境中。在成熟过程中添加半胱氨酸或硫化物会促进这种 H 簇状态的形成。此外，我们还发现观察到的类似 H 的物种的形成受到空间位阻和质子转移的影响，这突出了外配位球效应对 H 簇反应性的重要性。
