The characterization of soluble matrix proteins in selected human renal calculi using two-dimensional polyacrylamide gel electrophoresis.

In the current study a novel method of matrix extraction was utilized to permit the analysis of soluble matrix proteins of different types of kidney stones by two-dimensional electrophoresis. Two-dimensional polyacrylamide gel electrophoresis (SDS-PAGE) was performed on each soluble matrix protein sample resulting in a characteristic "map" of spots for each stone. The soluble matrix protein "map" was complex yet reproducible for each sample studied. The soluble matrix protein maps resembled urinary protein maps and stones of different crystalline content had significantly different matrix protein maps. The two-dimensional electrophoretic maps of matrix proteins extracted from calcium oxalate and uric acid calculi were similar to previously published two-dimensional electrophoretic maps of urinary proteins recovered from calcium oxalate and uric acid crystals. The majority of the protein maps were noteworthy for the presence of a low molecular weight pattern (MW less than 17,500 dalton) not seen in association with normal urinary protein maps. The significance of this pattern is not known but could be the result of degradation of larger proteins, evidence of renal tubular disease, or evidence of selective incorporation of low molecular weight proteins during stone formation.