Intercellular Macromolecules Containing Polysaccharides

Abstract

A survey is presented of the carbohydrate of intercellular spaces that is known to exist in the form of polysaccharide. This amounts to considering the polysaccharides made by connective tissue cells. The chemical structures of these polysaccharides are discussed in the cases in which they are known and regularities in patterns are noted. Such regularities make of these polysaccharides a natural group that may be related to the natural group of connective tissue cells that produce them. Viscosity is discussed as an important property of hyaluronate. The polyelectrolyte properties of these polysaccharides are considered in detail mainly from the point of view of their use in studying the polysaccharides, fractionating them, and accounting for their behavior in tissues. Polyelectrolyte properties are considered in connection with simple cations, micellar detergent cations, metachromatic dye cations, and protein cations. The existence of the polysaccharides in native tissues as compounds with proteins is discussed in detail, and with particular reference to the two cases most thoroughly studied, the chondroitin sulfate of cartilage and the hyaluronate of synovial fluid. A sharp distinction is drawn between compact and diffuse macromolecules by a contrast of tropocollagen and hyaluronate. The known proteinpolysaccharides of intercellular space are diffuse molecules. Experiments are described to show how hyaluronate hinders sedimentation, excludes compact macromolecules, or entangles with fibrils. Binding of water by connective tissue and elasticity of cartilage may be related to the tissue content of such diffuse macromolecules.