Immobilization of Membrane-Associated Protein Complexes on SERS-Active Nanomaterials for Structural and Dynamic Characterization

Exploring the structural basis of membrane proteins is significant for a deeper understanding of protein functions. In situ analysis of membrane proteins and their dynamics, however, still challenges conventional techniques. Here we report the first attempt to immobilize membrane protein complexes on surface-enhanced Raman scattering (SERS)-active supports, titanium dioxide-coated silver (Ag@TiO2) nanoparticles. Biocompatible immobilization of microsomal monooxygenase complexes is achieved through lipid fission and fusion. SERS activity of the Ag@TiO2 nanoparticles enables in situ monitoring of protein–protein electron transfer and enzyme catalysis in real time. Through SERS fingerprints of the monooxygenase redox centers, the correlations between these protein–ligand interactions and reactive oxygen species generation are revealed, providing novel insights into the molecular mechanisms underlying monooxygenase-mediated apoptotic regulation. This study offers a novel strategy to explore structure–function relationships of membrane protein complexes and has the potential to advance the development of novel reactive oxygen species-inducing drugs for cancer therapy.