This book treats a new, far-from-fully-developed area of molecular biophysics-enzyme physics. An attempt is made to survey this field, but primary consideration is given tothreeprob­ lems under investigation in the Polymer Structure Labaratory of the Institue of High-Molecular Compounds, Academy of Seiences ofthe USSR. The first problern is the genetic coding of the biologically fun.ctional structure of proteins. Its solution is based on physical theories of hydrophobic interactions. The second problern is the conformational properties of pro­ teins as the factor governing enzyme activity. The most direct methods for experimental investigation of questions in this area are optical, principally those involving natural and magnetic rota­ tion of the plane of polarization. A substantial portion of the book concerns optical activity; the Faraday effect is discussed in an appendix. The third problern is the manifestation of the cooperative properties of enzymes in the kinetics of enzymatic reactions and the solution of complex kinetic problems. This problern is espe­ cially pressing in connection with research on allosteric enzymes, which are responsible for feedback in metabolic processes. An appendix describes a new method for solving kinetic problems, based on the theory of graphs. This volume extends and details certain of the ideas ex­ pressed in my previous book, Molecules and Life: An Introduction to Molecular Biophysics, which was published in this series in 1965.