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Reactions of NADH Oxidation by Tetrazolium and Ubiquinone Catalyzed by Yeast Alcohol Dehydrogenase

Reactions of NADH Oxidation by Tetrazolium and Ubiquinone Catalyzed by Yeast Alcohol Dehydrogenase The processes of NADH oxidation by p-NTF violet and ubiquinone catalyzed by isolated yeast alcohol dehydrogenase in aqueous and water-alcohol buffer solutions were studied. In the presence of p-NTF in aqueous solution at a pH of 6–7, NADH oxidation was extremely slow due to inhibition of the enzyme by the remaining enzyme-bound hydrophobic product, formazan, which forms during the reduction of p-Nitrotetrazolium. However, when the medium was alkalinized to a pH of 8–9 or when alcohol (ethanol or isopropanol) was added, formazan was desorbed from the enzyme, leading to an increase in the NADH oxidation rate. It was assumed that this redox reaction can be used as the basis for colorimetric measurement of the activity of different alcohol dehydrogenases. Tetrazolium reduction by alcohol was not observed at any value within the entire pH range. NADH oxidation in the presence of the enzyme and ubiquinone was also slow, even with the addition of alcohol, but its rate increased when the medium was acidified to a pH of 5.5–6. When a Tris-phosphate buffer was replaced with HEPES, a quasi-vibrational process was observed: NADH oxidization with ubiquinone to NAD+ and its subsequent reverse recovery with alcohol to NADH. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Biochemistry and Microbiology Springer Journals

Reactions of NADH Oxidation by Tetrazolium and Ubiquinone Catalyzed by Yeast Alcohol Dehydrogenase

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Publisher
Springer Journals
Copyright
Copyright © 2018 by Pleiades Publishing, Inc.
Subject
Life Sciences; Biochemistry, general; Microbiology; Medical Microbiology
ISSN
0003-6838
eISSN
1608-3024
DOI
10.1134/S0003683818030067
Publisher site
See Article on Publisher Site

Abstract

The processes of NADH oxidation by p-NTF violet and ubiquinone catalyzed by isolated yeast alcohol dehydrogenase in aqueous and water-alcohol buffer solutions were studied. In the presence of p-NTF in aqueous solution at a pH of 6–7, NADH oxidation was extremely slow due to inhibition of the enzyme by the remaining enzyme-bound hydrophobic product, formazan, which forms during the reduction of p-Nitrotetrazolium. However, when the medium was alkalinized to a pH of 8–9 or when alcohol (ethanol or isopropanol) was added, formazan was desorbed from the enzyme, leading to an increase in the NADH oxidation rate. It was assumed that this redox reaction can be used as the basis for colorimetric measurement of the activity of different alcohol dehydrogenases. Tetrazolium reduction by alcohol was not observed at any value within the entire pH range. NADH oxidation in the presence of the enzyme and ubiquinone was also slow, even with the addition of alcohol, but its rate increased when the medium was acidified to a pH of 5.5–6. When a Tris-phosphate buffer was replaced with HEPES, a quasi-vibrational process was observed: NADH oxidization with ubiquinone to NAD+ and its subsequent reverse recovery with alcohol to NADH.

Journal

Applied Biochemistry and MicrobiologySpringer Journals

Published: Jun 1, 2018

References