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

Abstract

An electrochemical assay for the enzyme N-acetyl-β-D-glucosaminidase (NAGase) is described, using bare screen-printed carbon electrodes (SPCEs). The enzyme substrate, 1-naphthyl-N-acetyl-β-D-glucosaminide, was added to the NAGase-containing sample under hydrodynamic conditions and was hydrolysed to 1-naphthol, which was monitored amperometrically at an E_app of +650 mV versus SCE. A pH study revealed the apparent V_max for the assay to occur at pH 4.5, corresponding to an apparent substrate K_m of 0.28 mM. In order to be compatible with the analysis of biological fluids, a final operating pH of 5.4 was selected, and, using a data recording time of 100 s post-substrate addition, the assay gave a linear response (r² = 0.988) over the range 3.1 to 108 mU ml⁻¹ NAGase (RSD = 15.4%). This assay has the potential to monitor NAGase levels in a number of application areas.