Determination of GOT activity on nucleation and crystal growth of calcium oxalate

Crystal Size Distribution (CSD) and the yield of Calcium Oxalate Crystals in solutions with an admixture of 5 normal and 3 stone forming urines, were determined. A positive correlation was found between the median size, the number of particles and the overall inhibitory potentials of the urines toward calcium oxalate precipitation in vitro as reflected by Discriminating Index (DI) measurements. Incubation of two samples of stone formers' (SF) urines with glutamic-oxalacetic-transaminase (GOT) caused a reduction of aspartic acid concentration, an increase in glutamic acid concentration and a parallel decrease in the DI values. After 90 min of SF urine incubation with GOT the DI in three samples was improved and both the median size and number of particles reduced, by 28% and 45% respectively. These results could indicate that GOT activity changes the inhibitory power of the SF urine by transforming aspartic acid into glutamic acid, having thus most probably a part in the inhibition of CaOx stone formation.