Differentiation between different enzymes within one class is possible by plotting the relative reaction rates of an enzyme with a series of chromogenic or fluorogenic enzyme substrates as an array of gray-scale squares (see scheme). The characteristic enzyme fingerprints obtained for hydrolytic enzymes such as lipases, esterases, amidases, and epoxide hydrolases are reproducible and enzyme specific. Such fingerprints may be used in quality controls, batch identification, and as screening tools in enzyme discovery programs.