Artificial enzymes: tuning the activity of the Orange protein towards photocatalytic Hydrogen production

The proton reduction activity of Orange protein (Orp), a small bacterial metalloprotein harboring a unique molybdenum/copper (Mo/Cu) heterometallic cluster [S2MoS2CuS2MoS2]3–, was investigated. It exhibits excellent photocatalytic activity in the presence of ascorbate as electron donor and [Ru(bpy)3]Cl2 as photosensitizer. Assembling synthetic dinuclear [S2MS2M′S2MS2](4n)– clusters in the active sites allows to tune the activity of the system, when the implementation of a Mo/Fe core led to a record activity among artificial hydrogenases.