An assay for the enzyme N-acetyl-beta-D-glucosaminidase (NAGase) based on electrochemical detection using screen-printed carbon electrodes (SPCEs)

An electrochemical assay for the enzyme N-acetyl-beta -D-glucosaminidase (N AGase) is described, using bare screen-printed carbon electrodes (SPCEs). T he enzyme substrate, 1-naphthyl-N-acetyl-beta -D-glucosaminide, was added t o the NAGase-containing sample under hydrodynamic conditions and was hydrol ysed to 1-naphthol, which was monitored amperometrically at an E-app of +65 0 mV versus SCE. A pH study revealed the apparent V-max for the assay to oc cur at pH 4.5, corresponding to an apparent substrate K-m of 0.28 mM. In or der to be compatible with the analysis of biological fluids, a final operat ing pH of 5.4 was selected, and, using a data recording time of 100 s post- substrate addition, the assay gave a linear response (r(2) = 0.988) over th e range 3.1 to 108 mU ml(-1) NAGase (RSD = 15.4%). This assay has the poten tial to monitor NAGase levels in a number of application areas.