Properties of an alcohol dehydrogenase from the hyperthermophilic archaeon Aeropyrum pernix K1

A NAD +-dependent medium-chain alcohol dehydrogenase from the hyperthermophilic archaeon Aeropyrum pernix K1 was expressed in Escherichia coli and purified. The recombinant enzyme was a homotetramer of molecular mass 1.6×10 2 kDa. The optimum pH for the oxidative reaction was around 10.5 and that for the reductive reaction was around 8.0. The enzyme had a broad substrate specificity including aliphatic and aromatic alcohols, aliphatic and aromatic ketones, and benzylaldehyde. This enzyme produced ( S)-alcohols from the corresponding ketones. The enzyme was thermophilic and the catalytic activity increased up to 95°C. It maintained 24% of the original catalytic activity after incubation for 30 min at 98°C, indicating that this enzyme is highly thermostable.