Inhibitory effect of calcium phosphate-associated proteins on calcium oxalate crystallization: alpha2-HS-glycoprotein, prothrombin-F1 and osteopontin.

Abstract

To analyse urinary calcium phosphate- associated proteins and assess their inhibitory effects on calcium oxalate crystallization. Materials and methods Urine samples were collected over 24 h from five healthy men and calcium phosphate crystallization induced with NaOH solution. The bound proteins were separated on a cellulose column. To examine the effect of urinary calcium phosphate-associated proteins on calcium oxalate crystallization, 60 L of urine was collected from the healthy men. The effect of the separated fractions was studied in a mixed suspension/mixed product removal system. The separated proteins were identified as alpha2-HS-glycoprotein, prothrombin fragment 1 and osteopontin. Prothrombin fragment 1 and osteopontin strongly inhibited the growth of calcium oxalate crystals in artificial urine. alpha2-HS-glycoprotein, prothrombin fragment 1 and osteopontin selectively bound with calcium phosphate crystals in urine. Prothrombin fragment 1 and osteopontin in urine may strongly influence stone formation.