CO as a vibrational probe of heme protein active sites

Spiro, Thomas G.; Wasbotten, Ingar H.

doi:10.1016/j.jinorgbio.2004.09.026

Cited by 210 publications

(384 citation statements)

References 96 publications

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“…In fact, heme-bound CO is a sensitive probe for investigating distal and proximal effects on ligand binding of heme proteins since back-donation from the heme Fe(II) atom dp orbitals to the CO p* orbitals is modulated by polar interactions between the oxygen atom of the iron(II) heme bound CO and distal polar residues, and by a trans-ligand effect, i.e., variations in the donor strength of the trans ligand. As the back-donation increases, the Fe-C bond strengthens and the CO bond weakens, thereby increasing the m(Fe-CO) vibrational frequencies and decreasing the m(CO) frequencies [55][56][57].…”

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

“…The correlation plots have a negative slope and depend on the extent of p backbonding. Furthermore, since Fe-CO back-bonding is also modulated by variations in the donor strength of the trans axial ligand, changes in the trans ligand donor strength shift the correlation line and give rise to parallel lines at higher or lower positions in the correlation plot [55][56][57].…”

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

“…3, a plot of the m(Fe-CO) and m(CO) frequencies for CO adducts of a variety of ferrous heme proteins and heme model compounds having either a His residue as the fifth axial ligand or a weaker/absent trans ligand is shown [57]. The m(Fe-CO) stretching mode at 524 cm -1 and the m(CO) stretch at 1,960 cm -1 of the COiron(II) heme-HSA complex at pH 7.0 are located above the His line of the m(Fe-CO)/m(CO) back-bonding correlation, since the proximal ligand is either weak [55] or absent [56].…”

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

“…This result is consistent with the presence of a Tyr residue as the axial ligand. However, the correlation plot cannot effectively separate a five-coordinate CO-iron(II) heme system from a six-coordinate species with a weak proximal ligand, such as water or Tyr [57,58]. The m(Fe-CO)/m(CO) (Fig.…”

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

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Evidence for pH-dependent multiple conformers in iron(II) heme–human serum albumin: spectroscopic and kinetic investigation of carbon monoxide binding

et al. 2011

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Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

Section: Spectroscopic Properties Of Co-iron(ii) Heme-hsamentioning

confidence: 99%

See 2 more Smart Citations

Evidence for pH-dependent multiple conformers in iron(II) heme–human serum albumin: spectroscopic and kinetic investigation of carbon monoxide binding

et al. 2011

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“…Each substrate-bound P450arom, however, exhibits different reactivity to the molecular oxygen and different sensitivity to the inhibition by CO (40), allowing us to speculate that the heme environment of P450arom would depend on the substrates. To confirm this, we measured the absorption spectra for the ferrous-CO form of P450arom and tried to detect the CO-associated vibrations that are sensitive to the distal environment and the electronic property of the proximal ligand (29)(30)(31). Figure 4 illustrates the optical absorption spectra for the ferrous-CO forms of P450arom in the absence and presence a We cannot determine the specific peak position due to the overlapping with the Raman line from glycerol.…”

Section: Uv/vis Absorption Spectra Of Ferric P450arommentioning

confidence: 99%

Raman Evidence for Specific Substrate-Induced Structural Changes in the Heme Pocket of Human Cytochrome P450 Aromatase during the Three Consecutive Oxygen Activation Steps

et al. 2006

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Specific substrate-induced structural changes in the heme pocket are proposed for human cytochrome P450 aromatase (P450arom) which undergoes three consecutive oxygen activation steps. We have experimentally investigated this heme environment by resonance Raman spectra of both substratefree and substrate-bound forms of the purified enzyme. The Fe-CO stretching mode (ν Fe-CO ) of the CO complex and Fe 3+ -S stretching mode (ν Fe-S ) of the oxidized form were monitored as a structural marker of the distal and proximal sides of the heme, respectively. The ν Fe-CO mode was upshifted from 477 to 485 and to 490 cm -1 by the binding of androstenedione and 19-aldehyde-androstenedione, substrates for the first and third steps, respectively, whereas ν Fe-CO was not observed for P450arom with 19-hydroxyandrostenedione, a substrate for the second step, indicating that the heme distal site is very flexible and changes its structure depending on the substrate. The 19-aldehyde-androstenedione binding could reduce the electron donation from the axial thiolate, which was evident from the low-frequency shift of ν Fe-S by 5 cm -1 compared to that of androstenedione-bound P450arom. Changes in the environment in the heme distal site and the reduced electron donation from the axial thiolate upon 19-aldehydeandrostenedione binding might stabilize the ferric peroxo species, an active intermediate for the third step, with the suppression of the formation of compound I (Fe 4+ dO porphyrin +• ) that is the active species for the first and second steps. We, therefore, propose that the substrates can regulate the formation of alternative reaction intermediates by modulating the structure on both the heme distal and proximal sites in P450arom.

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Nuclear Resonance Vibrational Spectroscopy ( NRVS )

Zeng

Silvernail

Scheidt

et al. 2005

Encyclopedia of Inorganic Chemistry

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Nuclear Resonance Vibrational Spectroscopy (NRVS) utilizes the simultaneous excitation of the Mössbauer nucleus and vibrational quanta. Vibrational features appear as sidebands on the recoilless resonance. NRVS reveals the complete vibrational spectrum of the probe nucleus with the resolution almost equal to that of Raman or infrared. Major advantages include selectivity to vibrations of the Mössbauer isotope with quantitative information on vibrational amplitudes, as well as frequencies. Single crystal measurements are selective for motion along the exciting X‐ray beam. NRVS is equally applicable to all ligation and oxidation states. Questions that can be addressed include the strength of metal coordination, the energetic cost of probe displacement, discrimination of metal‐ligand vibrations from cofactor or peptide vibrations, and the local vs. global character of active site vibrations.

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CO as a vibrational probe of heme protein active sites

Cited by 210 publications

References 96 publications

Evidence for pH-dependent multiple conformers in iron(II) heme–human serum albumin: spectroscopic and kinetic investigation of carbon monoxide binding

Evidence for pH-dependent multiple conformers in iron(II) heme–human serum albumin: spectroscopic and kinetic investigation of carbon monoxide binding

Raman Evidence for Specific Substrate-Induced Structural Changes in the Heme Pocket of Human Cytochrome P450 Aromatase during the Three Consecutive Oxygen Activation Steps

Nuclear Resonance Vibrational Spectroscopy ( NRVS )

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