Partial Purification and Characterization of Aldehyde Dehydrogenase from Sweet Potato Roots

Abstract

Two kinds of aldehyde dehydrogenases were found in the supernatant fraction of extracts of sweet potato roots. These enzymes had different >Km values for acetaldehyde. The major enzyme, which had a low >Km value, was partially purified from fresh sweet potato roots by several steps, including phenyl-Sepharose column chromatography. Purification increased the specific activity 240-fold compared to that at the ammonium sulfate fractionation step. The molecular weight was calculated to be close to 150,000. In potassium phosphate buffer the optimal pH was approximately 8.0, and, in Tris-HCl buffer, it was approximately 8.8. The >Km value for acetaldehyde was 7.0 µM. According to the data obtained from phenyl-Sepharose column chromatography, the enzyme was rather amphipathic in spite of its being a soluble enzyme.