Kinetic Mechanism of Human Class IV Alcohol Dehydrogenase Functioning as Retinol Dehydrogenase
| Autor: | Ching-Long Lai, Shih-Jiun Yin, Chu-Fang Chou, Yen-Chun Chang, Gregg Duester |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
chemistry.chemical_classification
Ethanol biology Stereochemistry Alcohol Dehydrogenase Retinoic acid Dehydrogenase Cell Biology Retinol dehydrogenase Biochemistry Recombinant Proteins Substrate Specificity Alcohol Oxidoreductases Kinetics chemistry.chemical_compound Enzyme chemistry Product inhibition biology.protein Humans Molecular Biology Ternary complex Signal Transduction Alcohol dehydrogenase |
| Zdroj: | Journal of Biological Chemistry. 277:25209-25216 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m201947200 |
| Popis: | Molecular genetic studies have indicated that alcohol dehydrogenase may be involved in the synthesis of retinoic acid, a hormonal molecule regulating diverse cellular functions at the transcriptional level. Class IV alcohol dehydrogenase (ADH) has been reported to be the most efficient enzyme catalyzing oxidation of retinol in human ADH family. Initial velocity, product inhibition, and dead-end inhibition experiments were performed with the recombinant human class IV ADH to elucidate kinetic mechanism with all-trans-retinol and all-trans-retinal as natural substrates. Fluorescence quenching was titrated in formation of the binary and abortive ternary enzyme complexes. The minimal mechanism deduced from steady-state kinetic and equilibrium binding studies is best described as an asymmetric rapid equilibrium random mechanism with two dead-end ternary complexes for retinol oxidation and a rapid equilibrium ordered mechanism with one dead-end ternary complex for retinal reduction, a unique mechanistic form for zinc-containing ADHs in the medium chain dehydrogenase/reductase superfamily. Dissociation constants for the binary complexes as well as the productive and abortive ternary complexes determined from different experimental approaches are in reasonable agreement. Kinetic isotope effect studies suggest rate-limiting isomerization of the central ternary complexes in both reaction directions. The potential interference of retinol metabolism by ethanol through the ADH pathway may play a significant role in the pathogenesis of fetal alcohol syndrome and alcohol-related upper digestive tract cancer. |
| Databáze: | OpenAIRE |
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