Control of carbon monoxide dehydrogenase orientation by site-specific immobilization enables direct electrical contact between enzyme cofactor and solid surface.

Controlling the orientation of redox enzymes on electrode surfaces is essential in the development of direct electron transfer (DET)-based bioelectrocatalytic systems. The electron transfer (ET) distance varies according to the enzyme orientation when immobilized on an electrode surface, which influences the interfacial ET rate. We report control of the orientation of carbon monoxide dehydrogenase (CODH) as a model enzyme through the fusion of gold-binding peptide (gbp) at either the N- or the C-terminus, and at both termini to strengthen the binding interactions between the fusion enzyme and the gold surface. Key factors influenced by the gbp fusion site are described. Collectively, our data show that control of the CODH orientation on an electrode surface is achieved through the presence of dual tethering sites, which maintains the enzyme cofactor within a DET-available distance (<14 Å), thereby promoting DET at the enzyme-electrode interface.