Abstract:

Objective To establish the continuous monitoring method for urinary beta-D-galactosidase （GAL） activity using 2-chloro-4-nitrophenyl-beta-D-galactosidase （CNP-GAL）as substrate,and to investigate the value of GAL in the early diagnosis of renal tubular lesion. Methods Based on the generation of color substance upon the hydrolysis of substrate into 2-chloro-4-nitrophenol（CNP）,the optimal pH value,substrate concentration,reaction time and so on were analyzed. The continuous monitoring method for urinary GAL activity was established. Urinary GAL activities in renal tubular lesion patients（30 cases of secondary renal injury,36 cases of tubal nephritis,25 cases of renal carcinoma and 34 cases of renal cyst） and 80 healthy subjects （healthy control group）were determined. Results The continuous monitoring method for urinary GAL activity was established using citric acid buffer solution. The enzyme optimal pH value was 4.8,the optimal substrate concentration was 2.0 mmol/L,and the within-run and between-run coefficients of variation（CV）were 2.44% and 4.47%. The linear range was 3.2- 25.6 U/L,which can not be determined at GAL<1.6 U/L. Urinary GAL activities in patients with secondary renal injury,tubal nephritis and renal carcinoma were higher than those in healthy control group（P<0.05）,and there was no difference in renal cyst patients. Conclusions The continuous monitoring method for urinary GAL activity has good sensitivity,precision and simplicity,which is suitable for the early diagnosis of renal tubular lesion.

Key words: Beta-D-galactosidase, 2-Chloro-4-nitrophenyl-beta-D-galactosidase, Continuous monitoring method, Renal tubular lesion