Aldehyde dehydrogenase from baker′s yeast catalyses the reduction of pyridine nucleotides by several aldehydes. It catalyses the oxidation of a wide range of substrates, such as acetaldehyde, formaldehyde, propionaldehyde, n-butylaldehyde, isobutylaldehyde, n-valeraldehyde, caproaldehyde, benzaldehyde, glycoaldehyde, D-glyceraldehyde, malonic semialdehyde, and succinic aldehyde. The enzyme has been used to study the production of ethanol and isobutanol.

• Unit definition: One unit will oxidize 1,0 μmole of acetaldehyde to acetic acid per min at 25 °C at pH 8,0 in the presence of β-NAD⁺, potassium and thiols
• Reconstitution: Enzyme can be dissolved at 0,3 mg/ml in 100 mM Tris-HCl buffer (pH 8,0), containing 0,02% BSA
• Physical form: Contains lactose, potassium phosphate and citrate buffer salts, and mercaptosuccinic acid
• Form: Lyophilized powder
• Composition: Protein, ≥5,0% biuret

The enzyme has been used to study the production of ethanol and isobutanol. Ethanol concentration can be determined colorimentrically by monitoring the enzymatic reduction of NAD using alcohol dehydrogenase after preremoval of aldehyde by aldehyde dehydrogenase. Aldehyde dehydrogenase (ALDH) from sigma has been used to evaluate the effects of pear extracts on ALDH activity during the study of the effects and action mechanisms of korean pear on alcohol detoxification.

Aldehyde dehydrogenase is a tetramer and has several different isoforms. The enzyme tested in 0,01 M pyrophosphate buffer shows a sharp optimum around pH 9,3 with acetaldehyde as substrate. Potassium ions and cysteine are essential for the enzyme′s activity. Rubidium or NH₄⁺ can be substituted for K⁺, and glutathione for cysteine. Lithium, Na⁺, and Cs⁺ inhibit the reaction. Aldehyde dehydrogenase is inhibited by propylurea, crotonaldehyde, n-propyl isocyanate, cyclohexyl isocyanate, 1-n-propyl-1-[(4-chlorophenyl)sulphonyl]-3-n-propylurea, and 1-methyl-1-[(4-chlorophenyl)sulphonyl]-3-n-propylurea. The enzyme may be utilised to quantitate aldehydes present in blood.