Expression of the Caldariomyces fumago chloroperoxidase in Aspergillus niger and characterization of the recombinant enzyme

The Caldariomyces fumago chloroperoxidase was successfully expressed in Asp ergillus niger. The recombinant enzyme was produced in the culture medium a s an active protein and could be purified by a three-step purification proc edure. The catalytic behavior of recombinant chloroperoxidase (rCPO) was st udied and compared with that of native CPO. The specific chlorination activ ity (47 units/nmol) of rCPO and its pH optimum (pH 2.75) were very similar to those of native CPO. rCPO catalyzes the oxidation of various substrates in comparable yields and selectivities to native CPO. Indole was oxidized t o 2-oxindole with 99% selectivity and thioanisole to the corresponding R-su lfoxide (enantiomeric excess >98%). Incorporation of O-18 from labeled (H2O 2)-O-18 into the oxidized products was 100% in both cases.