There is great interest in unraveling action mechanisms of key enzymes in biological processes. In many cases, insight on such molecular events can be derived from conventional biophysical analyses of isolated enzymes and their substrates or protein partners. For example, members of the matrix metalloproteinases (MMP) family have been implicated in numerous aspects of the migration of inflammatory and cancer cells through connective tissues, not only by degrading extracellular matrix (ECM) components but also by processing various soluble mediators, promoting many disease states. This information is currently being utilized for the rationalization and design of novel therapeutics.