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2HPD: Crystal Structure Of Hemoprotein Domain Of P450bm-3, A Prototype For Microsomal P450's
Science (1993) 261 p.731-736» All references (3)
Cytochrome P450BM-3, a bacterial fatty acid monoxygenase, resembles the eukaryotic microsomal P450's and their flavoprotein reductase in primary structure and function. The three-dimensional structure of the hemoprotein domain of P450BM-3 was determined by x-ray diffraction and refined to an R factor of 16.9 percent at 2.0 angstrom resolution. The structure consists of an alph and a beta domain. The active site heme is accessible through a long hydrophobic channel formed primarily by the beta domain and the B' and F helices of the alpha domain. The two molecules in the asymmetric unit differ in conformation around the substrate binding pocket. Substantial differences between P450BM-3 and P450cam, the only other P450 structure available, are observed around the substrate binding pocket and the regions important for redox partner binding. A general mechanism for proton transfer in P450's is also proposed.