Increased calcium oxalate crystal nucleation and aggregation by peroxidized protein of human kidney stone matrix and renal cells

Kidney stone matrix protein fractions eluted from DEAE cellulose column showed increased oxalate binding activity and had negative correlation with reduced thiol content. Fraction 1 (eluted in Tris-HCl, pH 7.4) and fraction 3 (0.3 M NaCl in buffer) showed nucleation and aggregation-promoting properties while fraction 2 (0.05 M NaCl in buffer) showed an inhibitory effect in an in vitro crystallization system. On peroxidation, fractions 1 and 3 showed a further increase in the promoting effect whereas fraction 2 showed a reduction in the inhibitory effect of nucleation and aggregation of calcium oxalate crystals. Protein peroxidation was negatively correlated with the inhibitory activity of the protein on calcium oxalate nucleation and aggregation. A similar promoting effect of nucleation and aggregation was seen with mitochondria and nucleus after peroxidation. These studies suggested that peroxidation of protein or tissue had greater influence on the nucleation and aggregation property of calcium oxalate crystal growth. Received: 25 January 2000 / Accepted: 1 February 2001