Properties of the Membrane-Bound Quinoprotein Aldehyde Dehydrogenase from Acetobacter rancens

The n-alkane metabolizing strain Acetobacter rancens CCM 1774 possesses a dye-linked membrane-bound aldehyde dehydrogenase. The application of a sequential solubilization procedure at defined protein-detergent ratios allowed fast and effective purification without loss in enzyme activity. Both forms of aldehyde dehydrogenase—the membrane-bound and the solubilized enzyme— exhibited different properties, such as stability and electron transfer to cyto-chromes. By means of spectrophotometric investigations the presence of heme, FAD and other known groups in the purified enzyme could be excluded. Preliminary investigations with regard to the natural electron acceptor indicated the participation of PQQ in electron transfer. The fluorescence spectrum recorded for methanol extracts of the pure enzyme are comparable with those of adducts of PQQ. Inactivated aldehyde dehydrogenase could be reactivated by addition of these extracts, following saturation kinetics. Both enzyme forms catalyzed the oxidation of straigh...