Cobaltocene-mediated catalytic monooxygenation using holo and heme domain cytochrome P450 BM3.

The feasibility of replacing NADPH with 1,1'-dicarboxycobaltocene in the catalytic cycle of cytochrome P450 BM3 has been explored. Using the holoprotein, the surrogate mediator was observed to reduce both the FAD and FMN in the reductase domain, as well as the iron in the heme domain. In an electrochemical system, the mediator was able to support lauric acid hydroxylation at a rate of 16.5 nmol product/nmol enzyme/minute. Similar electron transfer and catalysis were observed for the heme domain alone in the presence of the metallocene; the turnover rate in this case was 1.8 nmol product/nmol enzyme/minute. Parallel studies under the same conditions using a previously reported cobalt sepulchrate mediator showed that the two systems give similar results for both the holoenzyme and the heme domain.