O 2 sensitivity and H 2 production activity of hydrogenases-A review.

Hydrogenases are metalloproteins capable of catalyzing the interconversion between molecular hydrogen and protons and electrons. The iron-sulfur clusters within the enzyme enable rapid relay of electrons which are either consumed or generated at the active site. Their unparalleled catalytic efficiency has attracted attention, especially for potential use in H ₂ production and/or fuel cell technologies. However, there are limitations to using hydrogenases, especially due to their high O ₂ sensitivity. The subclass, called [FeFe] hydrogenases, are particularly more vulnerable to O ₂ but proficient in H ₂ production. In this review, we provide an overview of mechanistic and protein engineering studies focused on understanding and enhancing O ₂ tolerance of the enzyme. The emphasis is on ongoing studies that attempt to overcome O ₂ sensitivity of the enzyme while it catalyzes H ₂ production in an aerobic environment. We also discuss pioneering attempts to utilize the enzyme in biological H ₂ production and other industrial processes, as well as our own perspective on future applications.
(© 2019 Wiley Periodicals, Inc.)