Optimization of capillary electrophoresis conditions for in-capillary enzyme-catalyzed microreactions Original Research Article

This paper describes the use of capillary electrophoresis (CE) to relate electrophoresis conditions of in-capillary enzyme-catalyzed microreactions to product distribution profiles. Migrating in a capillary under electrophoresis conditions, plugs of substrate and enzyme are injected separately, and allowed to react. A mathematical relation is obtained whereby the electrophoresis parameters, voltage (V), enzyme concentration [E], and mixing time of reaction (M) at the applied voltage, are correlated to product ratios. This concept is demonstrated using as a model system the conversion of nicotinamide adenine dinucleotide (NAD) to nicotinamide adenine dinucleotide, reduced form (NADH) in the oxidation of glucose-6-phosphate (glc-6-P) to 6-phosphogluconate by glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49). The simulated results are shown to be in good quantitative agreement with experimental data. These procedures provide a direct relationship between electrophoretic conditions and product distribution of microscale reactions using CE. This technique offers a new and versatile approach to analyzing enzymatic reactions on a microscale.