Optimization of capillary electrophoresis conditions for in-capillary enzyme-catalyzed microreactions

This paper describes the use of capillary electrophoresis (CE) to relate el ectrophoresis conditions of in-capillary enzyme-catalyzed microreactions to product distribution profiles. Migrating in a capillary under electrophore sis conditions, plugs of substrate and enzyme are injected separately, and allowed to react. A mathematical relation is obtained whereby the electroph oresis parameters, voltage (V), enzyme concentration [E], and mixing time o f reaction (M) at the applied voltage, are correlated to product ratios. Th is concept is demonstrated using as a model system the conversion of nicoti namide adenine dinucleotide (NAD) to nicotinamide adenine dinucleotide, red uced form (NADH) in the oxidation of glucose-6-phosphate (glc-B-P) to 6-pho sphogluconate by glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49). Th e simulated results are shown to be in good quantitative agreement with exp erimental data. These procedures provide a direct relationship between elec trophoretic conditions and product distribution of microscale reactions usi ng CE. This technique offers a new and versatile approach to analyzing enzy matic reactions on a microscale. (C) 1999 Elsevier Science B.V. All rights reserved.