A multinuclear NMR study of the interactions of cations with proteoglycans, heparin, and Ficoll.

Measurements of NMR relaxation rates of 23Na, 39K, 25Mg and 43Ca were used to evaluate the extent of cation binding in solution to bovine nasal cartilage proteoglycans, hog mucosal heparin, and Ficoll (Pharmacia). The two most important factors determining relaxation rates in the presence of the polymers examined were polymer concentration and charge density. We found that proteoglycans did not bind monovalent cations but did bind divalent cations to a relatively small extent. Heparin bound monovalent and divalent cations to a much greater extent. Assembly of glycosaminoglycan chains into proteoglycan aggregates had no effect on the extent of cation binding.