Decoupling Adsorption from Reactivity: Protein Unfolding Governs Peptide Bond Hydrolysis on Metal-Organic Framework...

Metal-organic frameworks (MOFs) are promising platforms for biomolecular applications due to their tunable structures, high surface areas, and catalytic functionality. Zr-based MOFs, in particular, exhibit protease-like activity; however, the interfacial factors governing protein adsorption onto MOF materials and their impact on peptide bond cleavage remain poorly understood. Here, we employ the luminescent two-dimensional metal-organic nanosheet LMOF-601 as a platform to investigate the interplay between protein adsorption and peptide bond hydrolysis. The nanosheet morphology of LMOF-601 enhances surface accessibility and minimizes diffusion limitations, enabling real-time investigation of protein-MOF interactions via linker-based luminescence. Using three proteins with distinct physicochemical properties (lysozyme, α-lactalbumin, and myoglobin) we combine adsorption isotherms, fluorescence spectroscopy, and bioinformatic analysis to probe interfacial behavior. We find that adsorption alone is insufficient to induce protein hydrolysis; instead, catalytic activity is associated with adsorption-induced structural adaptation that increases peptide bond accessibility to the Zr₆O₈ nodes. The extent of this adaptation correlates with intrinsic protein "softness," with myoglobin exhibiting the largest fluorescence response and undergoing selective cleavage by LMOF-601. These results establish a relationship between intrinsic protein properties and MOF-mediated hydrolysis and support a mechanistic framework in which interfacial adaptability, rather than adsorption strength alone, governs catalytic outcome. More broadly, this work highlights luminescent MONs as sensitive probes of protein-surface interactions and provides molecular-level insight to guide the design of selective MOF-based nanozymes for applications in biocatalysis and biomedicine.