Alcohol dehydrogenase 1 (Equus caballus) (HLADH) (HLADH)

Horse liver alcohol dehydrogenase (HLADH) is a dimeric, zinc-dependent oxidoreductase that serves as a primary model for the study of alcohol metabolism and enzyme kinetics. It catalyzes the reversible oxidation of a wide range of primary and secondary alcohols to their corresponding aldehydes and ketones, utilizing nicotinamide adenine dinucleotide (NAD+) as a cofactor (UniProt P00327). In clinical toxicology, the human ortholog of this enzyme is a critical therapeutic target; inhibiting its activity prevents the conversion of relatively non-toxic substances like methanol and ethylene glycol into highly toxic metabolites such as formic acid and oxalic acid (StatPearls, 2023). Fomepizole is a potent competitive inhibitor of HLADH and is the standard treatment for such poisonings (PubChem). Beyond its medical relevance, HLADH is extensively used in organic synthesis and industrial biocatalysis due to its broad substrate specificity and high degree of stereoselectivity (Journal of Biological Chemistry). The enzyme consists of two subunits, often designated E (ethanol-active) and S (steroid-active), which form various isoenzymes with distinct substrate preferences.

Other names

Horse liver alcohol dehydrogenaseAlcohol dehydrogenase E chainAlcohol dehydrogenase S chainADH1Alcohol:NAD+ oxidoreductaseLiver alcohol dehydrogenase

Competitive inhibition of the enzyme active site by binding to the catalytic zinc ion, thereby preventing the oxidation of alcohol substrates into their corresponding toxic aldehydes (StatPearls, 2023).