Double enzyme-catalyzed microreactors using capillary electrophoresis

This work evaluates the concept of a double enzyme-catalyzed microreactor using capillary electrophoresis (CE). Migrating in a capillary under electrophoresis conditions, plugs of substrate and two enzymes are injected separately in buffer and allowed to react. Extent of reaction and product ratios were subsequently determined by CE. This concept is demonstrated using two model systems: the conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and adenosine monophosphate (AMP) by hexokinase (HK, EC 2.7.1.1) and apyrase (APY, EC 3.6.1.5), respectively, in the conversion of glucose to glucose-6-phosphate and inorganic phosphate, respectively, and the conversion of nicotinamide adenine dinucleotide, reduced form (NADH), to nicotinamide adenine dinucleotide (NAD) and back to NADH by lactate dehydrogenase (LDH, EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), respectively, in the conversion of pyruvate to lactate and glucose-6-phosphate (glc-6-P) to 6-phosphogluconate, respectively. These procedures illustrate the use of the capillary as a double microreactor and the ease of quantitation of reaction products under conditions of electrophoresis.