IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt
Allosteric and Uncompetitive Inhibition of Yeast Alcohol Dehydrogenase Identified by Enzyme Kinetics
Abstract
Enzyme kinetics is a powerful technique used to quantify the rate at which an enzyme converts a substrate into a product and to identify potential inhibitors. In this study, kinetic analysis was employed to assess the activity of yeast alcohol dehydrogenase (YADH) in the presence and absence of sweeteners commonly found in alcoholic beverages. YADH catalyzes the oxidation of ethanol to acetaldehyde using NAD⁺ as a cofactor; the reduction to NADH can be monitored spectrophotometrically at 340 nm. Based on structural similarities to the ribose moiety of NAD⁺, it was hypothesized that sucrose and sucralose could directly interact with the enzyme or its cofactor, inhibiting YADH activity, resulting in a reduced rate of NADH formation. Specifically, the fructose component of sucrose was expected to interfere with the enzyme’s activity. Conversely, Splenda®, being 1.1% sucralose and primarily inert maltodextrin, was predicted to have minimal impact. Michaelis-Menten and Lineweaver-Burk plots were generated using varying ethanol concentrations to determine kinetic parameters and characterize inhibition when induced. Sucrose exhibited mixed inhibition resembling noncompetitive behavior, likely binding allosterically and altering enzyme activity without interfering with substrate binding. In contrast, Splenda exhibited uncompetitive inhibition, evidenced by parallel kinetic traces and proportional decreases in both Km and Vmax. These findings demonstrate an effective approach to identifying how dietary sweeteners influence YADH activity. The results suggest that sweeteners can directly slow the enzymatic metabolism of ethanol, even in a simplified in vitro system.
Recommended Citation
Harrison, Dylan Jeremy and Cappuccio, Jenny A.
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"Allosteric and Uncompetitive Inhibition of Yeast Alcohol Dehydrogenase Identified by Enzyme Kinetics,"
IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt: Vol. 9, Article 2.
Available at:
https://digitalcommons.humboldt.edu/ideafest/vol9/iss1/2