Compressibility and uncoupling of cytochrome P450cam: high pressure FTIR and activity studies.
The effect of the hydrostatic pressure on the CO ligand stretch vibration in cytochrome P450cam-CO bound with various substrates is studied by FTIR. The vibration frequency is linearily shifted to lower values with increasing pressure. The slope of the shift gives the isothermal compressibility of the heme pocket and is found to be related to the high-spin state content in an opposite direction to that previously observed from the pressure-induced shift of the Soret band. This opposite behaviour is explained by the dual effect of heme pocket water molecules both on the CO ligand and on electrostatic potentials produced by the protein at the distal side. The latter effect disturbs ligand-distal side contacts which are needed for a specific proton transfer in oxygen activation when dioxygen is the ligand. Their loss results in uncoupled H(2)O(2) formation.
Jung
Christiane
C
Max-Delbrück-Center for Molecular Medicine, Protein Dynamics Laboratory, Robert-Rössle-Strasse 10, 13125 Berlin, Germany. cjung@mdc-berlin.de
Kozin
Sergey A
SA
Canny
Bernard
B
Chervin
Jean-Claude
JC
Hoa
Gaston Hui Bon
GH
D019475:Camphor 5-Monooxygenase / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry*; D004789:Enzyme Activation; D006418:Heme / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D006874:Hydrostatic Pressure; D011487:Protein Conformation; D011489:Protein Denaturation; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013379:Substrate Specificity
D006418:Heme; D002248:Carbon Monoxide; D006861:Hydrogen Peroxide; D019475:Camphor 5-Monooxygenase