Molecular Biophysics of the Extracellular Matrix. Questo articolo non è disponibile.Molecular Biophysics of the Extracellular Matrix

Biopolymers, such as proteins and nucleic acids have been subjected to a rational succession of structural studies in which the determination of chemical compositions, link­ ages, and sequences is followed by investigations of molecu­ lar architecture and interactions. By the end of the 1960s the covalent structures of glycosaminoglycans and proteo­ glycans had been defined both within the carbohydrate chains and in respect to their linkages to protein. The scene was therefore set for successful probing of three­ dimensional shapes and intermolecular associations. For­ tunately, during the 1970s appropriate physical methods were themselves greatly increasing in power. Consequently much progress has been made using X-ray diffraction anal­ ysis of hydrated films, nuclear magnetic resonance spectro­ scopy, and chromatographie methods for investigation of molecular interactions in solution. We now have a great deal of information about molecular shapes, their sensitiv­ ity to environment (especially associated cations), and their modes of interaction that could be relevant to super­ molecular assemblies in biological milieux. For these rea­ sons we judged that it would be timely to distil the main conclusions from this phase of research to prepare for the next, which will involve detailed study of the interplay be­ tween biological function and molecular structure. The idea for this volume emerged from a workshop meeting at Colworth sponsored by the Biochemical Society.

1 Structure and Associations of Proteoglycans in Cartilage.- Structure.- Preparation.- Link-Free Aggregates.- Link-Stable Aggregates.- The Secretion and Assembly of Proteoglycan Aggregates.- Diversity of Proteoglycan Structure.- 2 The Dilute Solution Properties of Glycosaminoglycans and Proteoglycans.- The Relevance of the Term “Dilute Solution”.- Hyaluronate.- The Sulfated Glycosaminoglycans.- Proteoglycans.- Conclusions.- 3 X-Ray Diffraction Analyses of Glycosaminoglycans.- The Relevance of Fiber Diffraction Studies.- Accuracy and Precision in Fiber Diffraction Analyses.- Polymorphism of Glycosaminoglycan Helices.- Detailed Structural Studies of Hyaluronate Allomorphs.- Detailed Structural Studies of Chondroitin Sulfate Allomorphs.- Detailed Structural Studies of Dermatan Sulfate Allomorphs.- The Roles of Cations in Conformation and Packing.- Proteoglycans and Heterotypic Interactions.- Conclusions.- 4 Conformation of Individual Residues and Chain Segments of Glycosaminoglycans in Solution by Spectroscopic Methods.- Conformation of Individual Residues.- Conformation of Chain Segments.- 5 Self-Association of Copolymeric Glycosaminoglycans (Proteoglycans).- Dermatan Sulfate.- Affinity Chromatography.- Gel Chromatography.- Light Scattering.- Chemistry.- Heparan Sulfate.- Gel Chromatography.- Light Scattering.- Chemistry.- Proteodermatan Sulfate.- Extraction and Purification.- Characterization.- Characterization of the Proteoglycan Subfractions.- Self-Association of Scleral Proteoglycans.- 6 Transport of Molecules in Connective Tissue Polysaccharide Solutions.- The State of Polysaccharides in Connective Tissue.- Modes of Transport.- Diffusion in a Binary System.- Diffusional Transport Within a Homogeneous Polymer Matrix.- Transport Across a Matrix (or Membrane).- Transport in an Inhomogeneous Matrix.- Interpretation of Translational Transport Data.- Diffusion of Low Molecular Weight Solutes in Polymer Matrices—Concept of Microviscosity.- Mutual Diffusion of Macromolecular Solutes in a Binary System.- Diffusion of Macromolecular Solutes in Matrices.- Summarizing View.- Rotational Diffusion.- Transport of Electrolytes.- Simple Electrolytes.- Polyelectrolytes.- Formation and Transport of Matrix Structures.- Observation of Very Rapid Polymer Transport in Concentrated Ternary Systems.- Visualization of the Anomalous Transport.- A Tentative Explanation of the Phenomenon.- Biological Implications.- 7 Glycosaminoglycan Chains in the Biological State.- Introduction—Molecular Species.- Molecular Shapes.- Molecular Assemblies.- References.