ABSTRACT
Interest in the role of conformation changes, together with the use of energy trans duction for stabilizing new structures or chemical intermediates (not transition states) and changing equilibrium constants (not rate constants), has hitherto been more or less confined to allosteric enzymes such as pyruvate kinase (Chapter 8) and proteins such as hemoglobin (Chapter 9) or the Ca-binding signaling proteins (Chapter 5). However, it has long been realized that significant conformation changes and energy transduction will probably also play an important role in those enzymatic reactions which produce or require a significant amount of energy either for the overall reaction (e.g., ATPases, cytochrome oxidase) or for the production of a highenergy intermediate from the substrate (e.g., nitrogenase, see Sec. 2 .3 ), protein or cofactor (e.g., the Bi2-dependent mutases). The MgATPases (Sec. 2 .1 ) and Bi2-dependent mutases (Sec. 2 .2 ) have now provided the necessary experimental evidence.
