Characterisation of a Recombinant NADP‐Dependent Glycerol Dehydrogenase from Gluconobacter oxydans and its Application in the Production of L ‐Glyceraldehyde

The acetic acid bacterium Gluconobacter oxydans has a high potential for oxidoreductases with a variety of different catalytic abilities. One putative oxidoreductase gene codes for an enzyme with a high similarity to the NADP + ‐dependent glycerol dehydrogenase (GlyDH) from Hypocrea jecorina . Due to this homology, the GlyDH (Gox1615) has been cloned, over‐expressed in Escherichia coli , purified and characterised. Gox1615 shows an apparent native molecular mass of 39 kDa, which corresponds well to the mass of 37.213 kDa calculated from the primary structure. From HPLC measurements, a monomeric structure can be deduced. Kinetic parameters and the dependence of the activity on temperature and pH were determined. The enzyme shows a broad substrate spectrum in the reduction of different aliphatic, branched and aromatic aldehydes. Additionally, the enzyme has been shown to oxidize a variety of different alcohols. The highest activities were observed for the conversion of D ‐glyceraldehyde in the reductive and L ‐arabitol in the oxidative direction. Since high enantioselectivities were observed for the reduction of glyceraldehyde, the kinetic resolution of glyceraldehyde was investigated and found to yield enantiopure L ‐glyceraldehyde on preparative scale.