Defects in mitochondrial proteostasis contribute to many disorders, including cancer, neurodegeneration, and metabolic and genetic diseases. A strategy aimed at restoring the damaged mitochondrial proteostasis is the mitochondrion-targeting and carrier-free delivery of exogenous functional proteins that can replace the endogenous dysfunctional proteins. The modification of a protein with a photolabile protecting group (PPG, i.e., photocage group) can be activated in situ by response to illumination, leading to release of the protein from its photocage. Here, the Cys and peptide photocages with...