Functions of the carboxyl and sulfate groups of proteoglycans

Abstract

The extraction of hyaluronic acid, the natural protein-chondroitin-keratan sulfate complex, and proteoglycan aggregates from tissues is studied as a finction of the ionic strength of the extracting solution. It is shown that the strength of binding with the tissue diminishes in the following series: proteoglycan aggregates, protein-chondroitinkeratan sulfate, hyaluronic acid. Binding of proteoglycans with tissue structures is realized mainly by electrovalent interactions between sulfate groups of proteoglycan aggregates and protein-chondroitin-keratan sulfate, and positively charged tissue structures. It follows from data of infrared spectra that carboxyl groups of the macromolecules participate in the formation of both inner and outer hydrogen bonds with acetamide groups of the macromolecules. Carboxyl groups also play a role in the generation of soluble complexes with various bases. Rupture of linkage of proteoglycans with the tissue structures can result in their entry in the plasma and erythrocyte aggregation, and serve as evidence of a pathological process.