Crystal Inhibition:Binding of Heparin and Chondroitin Sulphate to Calcium Oxalate, Sodium Urate and Uric Acid Crystals

Abstract

Urinary glycosaminoglycans may be important inhibitors of calcium oxalate crystal growth and aggregation¹. These inhibitors may act by blocking the growth sites of the crystals and thereby prevent or delay crystal development. Calcium oxalate crystals, that had grown in human urine, have been found to contain chondroitin sulphate². Furthermore, a solid phase of sodium urate in urine has been suggested to act as an anti-inhibitor by binding urinary glycosaminoglycans and thereby reduce its inhibitory activity against calcium oxalate crystallisation^3,4. The binding of heparin to sodium urate crystals was also shown to be enhanced in the presence of divalent cations, such as calcium or magnesium⁵. We applied the principles used in receptor studies to examine the affinity of two potential inhibitors, heparin and chondroitin sulphate, to calcium oxalate, sodium urate and uric acid crystals.