The three enzyme system, alcohol (ADH), acetaldehyde (ALDH) and lactic (LDH) dehydrogenases, linked together by the reactant co-factor NAD, has been targeted in the form of a microreactor for the purpose of improving the rate of alcohol metabolism within the human body. Multi-enzyme system kinetic behavior and effective cofactor regeneration are important components of this system. In addition to the conversion of ethanol to acetaldehyde catalysed by ADH from S.cerevisiae (which is inhibited by acetaldehyde), this multi-enzyme system is successful due to its ability to convert acetaldehyde to acetate. Kinetic rate analysis with UV spectroscopy revealed that ALDH from S. cerevisiae exhibits strong substrate inhibition as a result of acetaldehyde. At modest or higher NADH concentrations the inhibition by acetaldehyde is greatly augmented, consequential of combined substrate and product inhibition from acetaldehyde/NADH complexations.

The rate of multi-enzyme ethanol conversion to acetate was high at relatively low acetaldehyde and NADH concentrations, while the rate of ethanol metabolism is considerably slowed at higher acetaldehyde and NADH concentrations. Computer simulations, which include the kinetic rate equations of each enzyme derived from experimental data, revealed that ALDH and LDH are critical to the successful metabolism of ethanol. The addition of these enzymes in the multienzyme process ultimately enables the maintenance of desirable ethanol conversion rates via ADH catalysis.

Future work will include immobilizing the three enzymes in a system capable of providing a protective capsule with appropriate enzyme loading.