Copper-hydroperoxido species (Cu-II-OOH) have been proposed to be key intermediates in biological and synthetic oxidations. Using biotin-streptavidin (Say) technology, artificial copper proteins have been developed to stabilize a Cu-II-OOH complex in solution and in aystallo. Stability is achieved because the Say host provides a local environment around the Cu-OOH that includes a network of hydrogen bonds to the hydroperoxido ligand. Systematic deletions of individual hydrogen bonds to the Cu-OOH complex were accomplished using different Say variants and demonstrated that stability is achieved with a single hydrogen bond to the proximal O atom of the hydroperoxido ligand: changing this interaction to only include the distal O-atom produced a reactive variant that oxidized an external substrate.