Functionally active membrane protein molecules in mesostructured silica films

Surfactant-directed mesostructured silicas are suitable abiotic host materials for the incorporation of functionally active membrane proteins in transparent and mechanically stable films. Judicious choices of conditions enable the light-responsive transmembrane protein proteorhodopsin to be stabilized in solution and subsequently co-assembled into silica−surfactant matrices with high protein loadings and retention of functional activity. Solid-state NMR yields well-resolved spectra that permit comparisons of the molecular structures and dynamics of proteorhodopsin in different host materials. Subtle variations are observed in the local protein structures and dynamics of regions that are associated with light-activated H⁺-ion pumping by proteorhodopsin molecules. Transient optical spectroscopy analyses yield apparent rate coefficients associated with interconversion of proteorhodopsin conformers during its photo-cycle, which are consistent with the native H⁺-pumping mechanism. The results establish the atomic-level structures and dynamics of functional proteorhodopsin molecules within abiotic mesostructured silica-surfactant host membranes and demonstrate the efficacy of these materials for harnessing functional membrane protein properties in robust abiological environments.