Synonym: ADH, Alcohol Dehydrogenase from yeast, Alcohol:NAD+ oxidoreductase
CAS Number: 9031-72-5
EC Number: 232-870-4
Enzyme Commission (EC) Number: 1.1.1.1
MDL Number: MFCD000813055
Unit Definition
One unit will convert 1.0 μmole of ethanol to acetaldehyde per min at pH 8.8 at 25 °C.
Physical Form
Solids containing <2% citrate buffer salts.
Biochem/physiol Actions
A 141 kDa tetramer containing 4 equal subunits. The active site of each subunit contains a zinc atom. Each active site also contains 2 reactive sulfhydryl groups and a histidine residue.
Isoelectric point: 5.4-5.8
Optimal pH: 8.6-9.0
Substrates: Yeast ADH is most active with ethanol and its activity decreases as the size of the alcohol increases or decreases. Branched chain alcohols and secondary alcohols also have very low activity.
KM (ethanol) = 2.1 × 10-3 M
KM (methanol = 1.3 × 10-1 M
KM (isopropanol) = 1.4 × 10-1 M
Inhibitors: Compounds that react with free sulfhydryls, including N-alkylmaleimides and iodoacetamide.
Zinc chelator inhibitors, including 1,10-phenanthroline,
8-hydroxyquinoline, 2,2′-dipyridyl, and thiourea.
Substrate analogue inhibitors, including β-NAD analogs, purine and pyrimidine derivatives, chloroethanol, and fluoroethanol.
Extinction Coefficient: E1% = 14.6 (water, 280 nm)
Yeast alcohol dehydrogenase (yADH) serves as an excellent model system for enzyme-catalyzed H transfer because unlike many other enzymes, the chemical step, oxidation of a primary alcohol to an aldehyde by NAD+, is rate-limiting with aromatic substrates.
Specifications
The dried enzyme has been stored for several weeks in a vacuum desiccator with little loss in activity. According to experiments described by A. Kornberg,3 the enzyme can be stored in the frozen state and can be thawed repeatedly without marked loss of activity.
Mol. Wt.: mol wt ~141,000 (four subunits)
Purified by: crystallization
Suitability: suitable for recycling micro-assay of β-NAD and β-NADH
Storage Temp.: −20°C