Fig. 5.
AhbD catalyzed Fe-coproporphyrin oxidase activity. HPLC traces of observed porphyrin derivatives at 390 nm in reaction containing, (A) Fe-coproporphyrin, cofactor mix, and cell-free extract of E. coli harboring empty expression vector, (B) Fe-coproporphyrin, cofactor mix, and cell-free extract of E. coli overexpressing D. desulfuricans AhbD, and (C) Fe-coproporphyrin, cell-free extract containing D. desulfuricans AhbD without AdoMet in the cofactor mix. Cofactor mix consisted of 500 µM AdoMet and NADPH with 0.3% (vol/vol) Triton X-100 in each assay. Fe-coproporphyrin was used at a final concentration of 25 µM, and is eluted as two close peaks from the HPLC column but with same m/z value of 708 by MS.