Urinary reservation and the enzymatic activity of r-glutamyltranspeptidase in human urine after freezing

Abstract

Urinary γ-glutamyltranspeptidase (γ-GTP) has been found to be unstable when stored at -20℃. When urine after freezing was subjected to cellulose acetate electrophoresis, β-band of two bands was diminished. Further, we observed that low activity of γ-GTP in human urine after freezing depend on the variant forms of the enzymes by condensation of the dialysate. We found that dialysis before freezing or addition of 5% dimethysulfoxide (DMSO) and 5% glycerol protected the enzyme activity against inactivation.