Entropy-Driven Processes in Biology

The purpose of this monograph is to bring together under one cover results of research on phenomena drawn from the fields of chemistry, biochemistry, bio physics, virology,and cell biology. The processes and reactions considered have one important feature in common: they are endothermic and, therefore, entropy driven. They are, in the main, reversible reactions leading to the formation of large structures, some of which play critical roles in life processes. If one thinks only of the subunits and of the structures they form upon poly merization, it seems to be a contradiction that such reactions can be driven by an increase in entropy; entropy is a measure of disorder. The increase in entropy must come from some other source, usually from the release of something coincidental to polymerization. That something has been shown to be water for the case of the polymerization of tobacco mosaic virus protein. Because of the remarkable similarity of the other processes to this one, it is a permissable inference that the release of water is the source of the entropy increase and therefore the driving force for all of them. The reactions and processes brought together in this book are still the sub jects of active research. ;~ny of the detailed interpretations presented here must be regarded as tentative, subject to modification as new information becomes available. However, the main characteristic of each reaction or pro cess, its endothermic or entropy-driven nature, is well established in all but one or two instances.

Contenu
1 The Nature of Entropy-Driven Processes.- Spontaneous Processes.- The Nature of Entropy.- Theory of Entropy-Driven Processes.- Entropic Unions.- Other Modes of Water Binding.- Complex Surface Elements.- Conformational Change.- Summary.- 2 The Role of Water.- Thermodynamic Definition of Hydration.- The Measurement of Changes in Hydration.- Volume Change in TMVP Polymerization.- Water Release upon Polymerization of TMVP.- Summary.- 3 Tobacco Mosaic Virus and Its Protein: Disc-Forming Polymerization.- Dissociation of Trimer.- General Preview of the Polymerization of TMV Protein.- Disc-Forming Polymerization of TMV Protein.- Linear Condensation Polymerization Mathematics.- Osmotic Pressure Studies.- Calorimetric Studies.- Effect of pH and Ionic Strength.- Volume Changes.- Structure of Double Discs.- Summary.- 4 Polymerization-Depolymerization of Tobacco Mosaic Virus Protein: Rod-Forming Polymerization.- Light Scatter.- Condensation Polymerization Mathematics.- Cooperativity.- Effect of pH.- The Effect of Ionic Strength.- The Effect of Various Chemicals.- Calorimetric Studies.- Summary.- 5 Polymerization-Depolymerization of the Proteins from Mutants of TMV and Other Viruses.- Cucumber Virus 4.- The Dahlemense Strain.- The PM2 Mutant.- Cucumber Green Mottle Mosaic Virus Protein.- Tobacco Rattle Virus.- Speculation on Models for Polymerization of Coat Protein of TMV and Its Strains.- Relation of Polymerization Behavior to Chemical Structure.- Summary.- 6 Reconstitution of TMV.- Mixed Reconstitution.- Synthesis of TMV in the Plant.- Calorimetric Studies.- Models for Reconstitution.- Reconstitution of Other Viruses.- Summary.- 7 Sickle Cell Anemia Hemoglobin.- Polymerization of Sickle Cell Hemoglobin.- Optical Rotatory Dispersion.- The Mechanism of Sickling.- Summary.- 8 Structural and Contractile Proteins.- Collagen.- Myosin.- Actin.- Interaction of Actin and Myosin.- Flagellin.- Summary.- 9 Other Entropy-Driven Reactions Involving Macromolecules.- Gels.- Soaps and Synthetic Detergents.- Antibodies.- Proteins and Synthetic Polypeptides.- Ion Binding by Proteins.- Precipitation of Proteins.- Thermal Denaturation of Proteins.- Interaction of DNA with Polyvalent Cations.- Summary.- 10 Entropy-Driven Processes in Biology.- Fertilized Eggs.- Formation of Pseudopodia in Amoebae.- Effects of ATP on Cleavage Capacity.- Color Changes in the Killifish.- Karyokinesis.- Effect of Heavy Water on the Mitotic Apparatus.- Effects of Colchicine.- The Axopodia of Heliozoa.- Relationship of Endothermic Cellular Processes to Microtubules.- Summary and Conclusions.- References.