Starting from the electromechanochemical principles of bioenergetics formulated by Green and Ji, a theory is proposed which describes enzymic catalysis in terms of piezoelectricity in semiconductors. The choice of this particular physical effect for describing catalytic processes is founded on the following experimental observations: most of the amino-acid residues of enzymes, as well as a large number of other biologically important molecules, exhibit piezoelectric resonances; besides, enzymes can behave like semiconductors. In the proposed theory the catalysis is assumed to be accomplished by means of three fundamental processes: (a) the lowering of the substrate-product energy barrier; (b) the electroninduced selective amplification of the low-frequency vibrational waves present in thermal background in the enzyme structure; and (c) the channeling into the substrate of the energy associated with the amplified waves and utilization of this energy for generating electrical or mechanical fields inside a susceptible region of the substrate. A mathematical description of the theory is outlined, and a rough estimate of some quantities involved in the process of wave amplification is also reported.The search for a unitary principle underlying enzymic catalysis is one of the most intriguing problems of contemporary biology (1, 2). Many models have been proposed for explaining enzyme catalytic power and enzyme specificity, but, as Reiner properly observed (3), the proposed theories are partial in that none of them embraces all the known facts in the framework of a unified treatment.The electromechanochemical (EMC) theory of bioenergetic processes, recently formulated by Green and Ji (4-7), is a wellordered set of principles which, when applied to the enzymic catalysis, provide a powerful tool for the overcoming of any partial view about the catalytic processes.Limitations of space prevent us from discussing those principles extensively; therefore, we shall only mention three fundamental concepts upon which the EMC theory is based. First, enzymes are visualized as macromolecular devices that episodically and impermanently convert thermal energy of the environment into EMC potential energy of the enzymic system. Second, the EMC energy is directed to the polarization of a susceptible bond of the substrate and is used for this purpose within the lifetime of the energized state. Third, enzymes possess a high informational content by means of Abbreviations: EMC, electromechanochemical; PE, piezoelectric. t Present address: Divisione Applicazioni Radiazioni, C. S. N.Casaccia, Casella Postale 2400, 00100 Roma, Italy. 4421 which all the maneuvers enabling the substrate-product conversion are controlled; this informational content is expressed by the concept of negative entropy, which measures the nonstatistical order of living systems.The intrinsic physical nature of the EMC theory prompted us to explore the possibility of rationalizing enzymic catalysis in terms of some solid-state physics phenomena with the main...
