Storage-stable compositions for generating antimicrobial activity are described. The compositions comprise an enzyme that is able to convert a substrate to release hydrogen peroxide, and a substance that includes a substrate for the enzyme. In certain embodiments, the enzyme is a purified enzyme. The storage-stable compositions do not include sufficient free water to allow the enzyme to convert the substrate. Use of the compositions to treat microbial infections and wounds is described, as well as methods for their production.
