Based on recognized principles of catalysis in chemical engineering that have been applied to development and design of important industrial processes, this article shows how it is possible to devise a methodology for treating complex enzyme systems. The method is illustrated by examples from both fields. With the reaction catalyzed by the enzyme dihydrofolate reductase, a cancer tumor target, as an example, we demonstrate how information on the rates of component elementary steps can be used to identify those that are most significant in promoting the activity of a given enzyme strain. In this way a tool is available for improved enzyme design.