Purification and Properties of Lactaldehyde Dehydrogenase from Escherichia coli

Abstract

Abstract An aldehyde dehydrogenase capable of acting on l-lactaldehyde was detected in a strain of Escherichia coli K-12 selected to grow on 1,2-propanediol as the sole source of carbon and energy. This enzyme activity was purified over 200-fold by ammonium sulfate fractionation followed by diethylaminoethyl cellulose chromatography, Sephadex G-100 gel filtration, and DEAE-Sephadex chromatography. The purified enzyme appears different from the other known aldehyde dehydrogenases in that it specifically converts l-lactaldehyde to lactic acid. This enzyme uses NAD as coenzyme, has a high Km for l-lactaldehyde, and displays a broad pH optimum in the alkaline region. It is produced constitutively by the above bacterial mutant and is essential for the catabolism of 1,2-propanediol.