Enhancement of the Sensitivity of a Fluorometric Lysozyme Assay System by Adding β-N-Acetylhexosaminidase

Abstract

The lysozyme assay using 4-methylumbelliferyl tetra-N-acetyl-β-chitotetraoside as a substrate was found to show increased sensitivity for lysozyme in the presence of jack bean β-N-acetylhexosaminidase (NAHase). The assay system containing NAHase gave a linear dose-response curve in the range of 10-70μg of lysozyme under conditions of 20-60 min incubation at pH 5.2 and 35°C, and the sensitivity for lysozyme was more than five times higher than that of the fluorometric assay system without the hexosaminidase. The new assay gave values compatible with those of the cell turbidimetric assay using Micrococcus lysodeikticus as a substrate in the estimation of lysozyme in pharmaceutical preparations. The present assay system has better reproducibility than the cell turbidimetric assay and may serve as a substitute for the latter.