FMN-reducing and FMN-oxidizing configurations in cytochrome 450
reductase may require a conformational change for interconversion.
(A) In cytochrome P450 reductase, electrons are
transferred from FAD to FMN in an interdomain reaction. In the
structure of cytochrome P450 reductase (10), the FAD and FMN cofactors
of the flavodoxin reductase-like (green) and flavodoxin-like (gray)
domains are juxtaposed for this electron transfer. Van der Waals
contacts between these domains of cytochrome P450 reductase are mapped
by homology onto the structure of E. coli flavodoxin,
which is shown in the same orientation as in Fig. 3. (B)
In cytochrome P450BM-3, electrons are transferred from FMN to the heme
in an interdomain reaction. In the structure of the
heme/FMN-containing fragment of cytochrome P450BM-3 (34), the
FMN-containing domain (gray) is juxtaposed against the heme-containing
domain (red) for electron transfer. Van der Waals contacts between
these domains of cytochrome P450 BM-3 are mapped by homology onto the
structure of E. coli flavodoxin, which is shown in the
same orientation as in Fig. 3.