title: Offline and online capillary electrophoresis enzyme assays of β-N-acetylhexosaminidase.
abstract: Enzyme assays of β-N-acetylhexosaminidase from Aspergillus oryzae using capillary electrophoresis in the offline and online setup have been developed. The pH value and concentration of the borate-based background electrolyte were optimized in order to achieve baseline separation of N,N',N″-triacetylchitotriose, N,N'-diacetylchitobiose, and N-acetyl-D-glucosamine. The optimized method using 25 mM tetraborate buffer, pH 10.0, was evaluated in terms of repeatability, limits of detection, quantification, and linearity. The method was successfully applied to the offline enzyme assay of β-N-acetylhexosaminidase, which was demonstrated by monitoring the hydrolysis of N,N',N″-triacetylchitotriose. The presented method was also utilized to study the pH dependence of enzyme activity. An online assay with N,N'-diacetylchitobiose as a substrate was developed using the Transverse Diffusion of Laminar Flow Profiles model to optimize the injection sequence and in-capillary mixing of substrate and enzyme plugs. The experimental results were in good agreement with predictions of the model. The online assay was successfully used to observe the inhibition effect of N,N'-dimethylformamide on the activity of β-N-acetylhexosaminidase with nanoliter volumes of reagents used per run and a high degree of automation. After adjustment of background electrolyte pH, an online assay with N,N',N″-triacetylchitotriose as a substrate was also performed.
authors: Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Prague, Czech Republic. krizek@natur.cuni.cz
authors: Tomáš
authors: T
authors: Křížek
authors: Veronika
authors: V
authors: Doubnerová
authors: Helena
authors: H
authors: Ryšlavá
authors: Pavel
authors: P
authors: Coufal
authors: Zuzana
authors: Z
authors: Bosáková
mesh_terms: D001236:Aspergillus oryzae / Q000737:chemistry / Q000201:enzymology*; D001331:Automation; D019075:Electrophoresis, Capillary / Q000379:methods*; D057075:Enzyme Assays / Q000379:methods*; D005656:Fungal Proteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D001619:beta-N-Acetylhexosaminidases / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D001619:beta-N-Acetylhexosaminidases