Porcine D-amino acid oxidase: production of the biologically active enzyme in Escherichia coli

DNA molecules coding either for mature porcine D-amino acid oxidase or for truncated forms of the enzyme have been obtained by stepwise addition of synthetic oligonucleotides to a partial cDNA. Under the control of the lambda PL thermoregulatable promoter, these DNAs were respectively expressed in Escherichia coli as 36, 28 and 25 kilodalton polypeptides, specifically recognised by antibodies raised against the natural enzyme. None of the truncated proteins were biologically active whereas the mature recombinant species was able to hydrolyze D-alanine in vitro as efficiently as the natural product.