The catalytic pathway of cytochrome p450cam at atomic resolution.

@article{Schlichting2000TheCP,
  title={The catalytic pathway of cytochrome p450cam at atomic resolution.},
  author={Ilme Schlichting and Joel Berendzen and Kelvin Chu and Ann M Stock and Shelley A. Maves and David E. Benson and Robert M. Sweet and Dagmar Ringe and Gregory A. Petsko and Stephen G. Sligar},
  journal={Science},
  year={2000},
  volume={287 5458},
  pages={
          1615-22
        }
}
Members of the cytochrome P450 superfamily catalyze the addition of molecular oxygen to nonactivated hydrocarbons at physiological temperature-a reaction that requires high temperature to proceed in the absence of a catalyst. Structures were obtained for three intermediates in the hydroxylation reaction of camphor by P450cam with trapping techniques and cryocrystallography. The structure of the ferrous dioxygen adduct of P450cam was determined with 0.91 angstrom wavelength x-rays; irradiation… 

MECHANISTIC ENZYMOLOGY OF OXYGEN ACTIVATION BY THE CYTOCHROMES P450

The detailed mechanism of P450 dioxygen scission is discussed utilizing the CYP101 hydroxylation of camphor as a model system and a structural and spectroscopic analysis of the nature of critical intermediate states in the reaction is discussed.

Activation of Molecular Oxygen in Cytochromes P450

The complex multistep mechanism of oxygen activation in P450 is reviewed as a sequence of the following reactions: Substrate binding, reduction of the heme iron from ferric to the ferrous state, binding of dioxygen, second electron transfer and formation of peroxo-ferric intermediate, and finally, after O–O bond scission, the ferryl-oxo intermediate.

Intermediates in P450 catalysis

  • T. Poulos
  • Chemistry
    Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2005
Cytochromes P450 catalyse the insertion of one O2-derived oxygen atom in unactivated C–H bonds, and as such, are potent oxidants. A significant amount is known about the P450 catalytic cycle owing

Mechanisms of reaction in cytochrome P450: Hydroxylation of camphor in P450cam.

The fundamental nature of reactivity in cytochrome P450 enzymes is currently controversial. Modelling of bacterial P450cam has suggested an important role for the haem propionates in the catalysis,

Oxygen activation by cytochrome P450 monooxygenase

Recent advances in understanding the molecular mechanisms by which P450 activates dioxygen are reviewed, finding similarities to PSII in proton delivery networks, oxygen and water access channels, and consecutive electron transfer processes.

The Proton Relay Network in the Bacterial P450s: CYP101A1 and CYP101D1.

A series of mutagenic, crystallographic, kinetic and molecular dynamics studies indicate that this mutation locks P450cam into a closed inactive conformation, opening a window into the critical proton coupled electron step in P450 catalysis.

Delicate conformational balance of the redox enzyme cytochrome P450cam

Using paramagnetic NMR spectroscopy with a lanthanoid tag, it is shown that the enzyme bound to its redox partner, putidaredoxin, is in a closed state at ambient temperature in solution, which supports a model of catalysis in which the substrate is locked in the active site pocket and the enzyme acts as an insulator for the reactive intermediates of the reaction.

Peripheral heme substituents control the hydrogen-atom abstraction chemistry in cytochromes P450

The results reveal that the enzyme catalyzes the hydrogen-atom abstraction step with a remarkably low free-energy barrier, providing a satisfactory explanation for the experimental failure to trap the proposed catalytically competent high-valent heme Fe(IV) oxo (oxyferryl) species responsible for this hydroxylation chemistry.
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References

SHOWING 1-10 OF 56 REFERENCES

Cytochrome P450cam: crystallography, oxygen activation, and electron transfer1

  • T. PoulosR. Raag
  • Chemistry
    FASEB journal : official publication of the Federation of American Societies for Experimental Biology
  • 1992
Several crystal structures of various substrate and inhibited complexes of the camphor monoxygenase, cytochrome P450cam from Pseudomonas putida, are now available. These structures, together with

Reduced oxy intermediate observed in D251N cytochrome P450cam.

Cytochrome P450s are ubiquitous heme proteins responsible for various oxidative metabolic processes and a new intermediate is observed in the UV-visible spectrum during catalytic turnover that is one electron reduced from oxy-P450 with an intact dioxygen bond.

Investigation of the proton-assisted pathway to formation of the catalytically active, ferryl species of P450s by molecular dynamics studies of P450eryF.

Three additional studies lend credibility to the important mechanistic inferences from the simulations of the transient twice reduced dioxygen species: further evidence for a proton-assisted pathway from it to the catalytically active ferryl species and a possible source of the protons.

Molecular recognition in cytochrome P-450: mechanism for the control of uncoupling reactions.

The increased commitment to catalysis observed for all mutants suggests that active-site hydration is important in the uncoupling to form hydrogen peroxide at the second branch point, as expected if the two-electron-reduced dioxygen-bound intermediate is not directly participating in the substrate activation step.

Understanding the role of the essential Asp251 in cytochrome p450cam using site-directed mutagenesis, crystallography, and kinetic solvent isotope effect.

Results indicate that Asp251 is an essential part of the normal proton delivery machinery required for O-O bond scission, and a role for an acid functionality in generation of iron-oxygen reactive intermediates is suggested.

Single turnover studies with oxy-cytochrome P-450cam.

Changes in secondary structure and salt links of cytochrome P-450cam induced by photoreduction: a Fourier transform infrared spectroscopic study.

The reduced-minus-oxidized difference spectra show that not only the heme group but also the protein backbone and individual amino acid side chains were affected by the redox transition.
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