Book excerpt: This book covers the most recent developments in the analysis of allosteric enzymes and provides a logical introduction to the limits for enzyme function as dictated by the factors that are limits for life. The book presents a complete description of all the mechanisms used for changing enzyme activity. It is extensively illustrated to clarify kinetic and regulatory properties. Eight enzymes are used as model systems after extensive study of their mechanisms. Wherever possible, the human form of the enzyme is used to illustrate the regulatory features.