Production of Recombinant Human Aldehyde Oxidase in Escherichia coli and Optimization of Its Application for the Preparative Synthesis of Oxidized Drug Metabolites

Recombinant human aldehyde oxidase (AO) was expressed in Escherichia coli. Different cell disruption methods and conditions of cell culture in shake flasks and bioreactors and of biotransformation on an analytical scale were tested to optimize the synthesis of oxidized AO drug metabolites. The volumetric productivity was increased 24-fold by optimizing the cell culture conditions. The highest yield was achieved in a 25L stirred tank bioreactor under non-oxygen-limited conditions and high lactose feed rate. Suspensions of highly concentrated and well-aerated whole cells at neutral pH and relatively low temperatures led to the best conversion. The solvent for the substrate and the buffering agent for the biotransformation had an important effect. In a biotransformation with AO, 210mg of famciclovir was converted to diacetyl penciclovir a yield of 82%. The optimized protocol represents a viable method for the preparative synthesis of oxidized AO metabolites of drugs.