Hydrogenases are enzymes that flatten the free energy change for the H-H bond formation and dissociation in water environments and at room conditions. The reduction of two protons to the H2 molecule, catalyzed by [FeFe]-hydrogenase, is an important reaction that allows the usage of microorganisms or electrocatalysis to produce a sustainable fuel by water [1]. The [FeFe]-hydrogenase HYDA1 enzyme of the unicellular alga Chlamydomonas rheinardtii (CR) is very efficient in reducing protons to molecular hydrogen, but it is very sensitive to dioxygen, that irreversibly demolishes the enzyme [2]. In this contribution the mechanism for H2 activation by [NiFe]-hydrogenase and that for proton reduction in [FeFe]-hydrogenase are described and contrasted, on the basis of first-principle molecular dynamics simulations [3]. The macromolecular effects of the HYDA1 protein matrix is investigated by empirical molecular dynamics. The two levels are integrated, in order to understand the effects of the disordered N-terminal chain on the accessibility of the active site, and to propose a design for a more dioxygen-tolerant [FeFe]-hydrogenase.
Understanding the mechanism of hydrogenases
La Penna;Giovanni
2012
Abstract
Hydrogenases are enzymes that flatten the free energy change for the H-H bond formation and dissociation in water environments and at room conditions. The reduction of two protons to the H2 molecule, catalyzed by [FeFe]-hydrogenase, is an important reaction that allows the usage of microorganisms or electrocatalysis to produce a sustainable fuel by water [1]. The [FeFe]-hydrogenase HYDA1 enzyme of the unicellular alga Chlamydomonas rheinardtii (CR) is very efficient in reducing protons to molecular hydrogen, but it is very sensitive to dioxygen, that irreversibly demolishes the enzyme [2]. In this contribution the mechanism for H2 activation by [NiFe]-hydrogenase and that for proton reduction in [FeFe]-hydrogenase are described and contrasted, on the basis of first-principle molecular dynamics simulations [3]. The macromolecular effects of the HYDA1 protein matrix is investigated by empirical molecular dynamics. The two levels are integrated, in order to understand the effects of the disordered N-terminal chain on the accessibility of the active site, and to propose a design for a more dioxygen-tolerant [FeFe]-hydrogenase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
