From Folding Reagents to Catalysts: Spatially Organized Diselenide−Cyclodextrins Enable Catalytic Oxidative Protein Folding

Abstract Oxidative folding, involving disulfide (SS) bond formation and isomerization, is essential for the maturation of many secreted and membrane proteins. Although numerous small-molecule mimics of protein disulfide isomerase, a key enzyme that catalyzes oxidative folding, have been developed, most require superstoichiometric amounts relative to the substrate. Here, we report cyclodextrin (CD)diselenide conjugates that create artificial folding reaction fields by spatially integrating substrate capture with redox catalysis within a topology-preserving bivalent architecture. Systematic variation of CD size, substitution pattern, and linker structure identified a γ-CDcyclic diselenide conjugate bearing two hydrophobic inclusion sites as the most effective catalyst across multiple model proteins. Mechanistic studies suggest that this bivalent architecture maintains a multivalent substrate-capture environment throughout the redox cycle, organizing protein thiols and mispaired SS bonds near the redox center to promote both SS formation and isomerization while suppressing aggregation. This reaction-field design transforms conventional folding reagents into true catalysts and establishes a molecular design principle for catalytic oxidative protein folding and the efficient production of SS-rich proteins.