Crystal Structure of Hemoprotein Domain of P450BM-3, a Prototype for Microsomal P450's

• Published in: Science (American Association for the Advancement of Science) 1993-08, Vol.261 (5122), p.731-736
• Main Authors: Ravichandran, Kurumbail G., Boddupalli, Sekhar S., Hasemann, Charles A., Peterson, Julian A., Deisenhofer, Johann
• Format: Article
• Language: English
• Subjects: Active sites; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Atoms; Bacillus megaterium; Bacterial Proteins; Binding Sites; Biological and medical sciences; Computer Graphics; Crystallization; Crystals; Cytochrome P-450; Cytochrome P-450 Enzyme System - chemistry; Cytochromes; Enzymes; Fatty acids; Fundamental and applied biological sciences. Psychology; Heme - chemistry; Hemoproteins; Metalloproteins; Mixed Function Oxygenases - chemistry; Models, Molecular; Molecular Sequence Data; Molecules; NADPH-Ferrihemoprotein Reductase; Oxygen; Physiological aspects; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Protons; Research Article; Sequence Alignment; Solvents; X-Ray Diffraction
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.8342039

Cytochrome P450BM-3, a bacterial fatty acid monooxygenase, 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 α and a β domain. The active site heme is accessible through a long hydrophobic channel formed primarily by the β domain and the B′ and F helices of the α 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.