Fluorimetric determination of activity and isoenzyme composition of N-acetyl-β-D-hexosaminidase in seminal plasma of fertile men and infertile patients with secretory azoospermia

Background: The activity and isoenzyme composition of N-acetyl-beta-D-hexosaminidase (EC.3.2.1.52) in seminal plasma of fertile and infertile men have been evaluated. However, no data are available on the isoenzyme content in seminal plasma from patients with secretory azoospermia. Methods: The activity and isoenzyme composition of seminal plasma from 15 normozoospermic controls and 18 patients with secretory azoospermia were determined by fluorimetric methods. 4-Methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside and 4-methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside-6-sulfate were used as fluorigenic substrates. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficiency of the assays. Results: No significant difference was found in total enzyme activity between the two groups, while isoenzyme A activity was significantly lower (p = 0.004) and the ratio between total enzyme activity and isoenzyme A activity was significantly higher (p = 0.04) in azoospermic patients compared to controls. The diagnostic efficiency of these evaluations was low (<= 75.7%). Conclusions: Our findings show that the isoenzyme composition of N-acetyl-beta-D-hexosaminidase in seminal plasma from patients with secretory azoospermia is significantly different from controls, but this difference does not represent a useful marker of secretory azoospermia. The fluorimetric assays are simple and rapid methods for evaluating the isoenzyme composition.