Immobilization\nof Membrane-Associated Protein Complexes\non SERS-Active Nanomaterials for Structural and Dynamic Characterization

Exploring\nthe structural basis of membrane proteins is significant\nfor a deeper understanding of protein functions. In situ analysis\nof membrane proteins and their dynamics, however, still challenges\nconventional techniques. Here we report the first attempt to immobilize\nmembrane protein complexes on surface-enhanced Raman scattering (SERS)-active\nsupports, titanium dioxide-coated silver (Ag@TiO<sub>2</sub>) nanoparticles.\nBiocompatible immobilization of microsomal monooxygenase complexes\nis achieved through lipid fission and fusion. SERS activity of the\nAg@TiO<sub>2</sub> nanoparticles enables in situ monitoring of protein–protein\nelectron transfer and enzyme catalysis in real time. Through SERS\nfingerprints of the monooxygenase redox centers, the correlations\nbetween these protein–ligand interactions and reactive oxygen\nspecies generation are revealed, providing novel insights into the\nmolecular mechanisms underlying monooxygenase-mediated apoptotic regulation.\nThis study offers a novel strategy to explore structure–function\nrelationships of membrane protein complexes and has the potential\nto advance the development of novel reactive oxygen species-inducing\ndrugs for cancer therapy.