Fragmentation of heme and hemin+ with sequential loss of carboxymethyl groups: A DFT and mass-spectrometry study

Чаркин, О. П.; Клименко, Н. М.; Nguyen, Phuong Thu; Charkin, Dmitri O.; Mebel, Alexander M.; Lin, Sheng Hsien; Wang, Yi-Sheng; Wei, Shuxian; Chang, Huan‐Cheng

doi:10.1016/j.cplett.2005.09.036

Cited by 37 publications

(40 citation statements)

References 14 publications

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“…8,9 Wang and co-workers 10 characterized copper-phtalocyanine anions based on photoelectron spec-troscopy. 12 This is in accordance with previous experimental 14 and theoretical works 15,16 where such ␤-cleavage in heme + is found to be the lowestenergy channel for fragmentation. 11 Furthermore, our work containing the absorption spectra and fragmentation spectra of Fe͑III͒-heme + and Fe͑III͒-heme + ͑his͒ ͑his denotes histidine͒ in the Soret band region was recently published.…”

Section: Introductionsupporting

confidence: 88%

“…12,[15][16][17] Considering the proton affinities of imidazole ͑943 kJ/mol͒ and glycine ͑887 kJ/mol͒, it is clear that the histidine is bound to the iron center of heme at the imidazole end ͑see Fig. 12,[15][16][17] Considering the proton affinities of imidazole ͑943 kJ/mol͒ and glycine ͑887 kJ/mol͒, it is clear that the histidine is bound to the iron center of heme at the imidazole end ͑see Fig.…”

Section: Resultsmentioning

confidence: 99%

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Absorption in the Q-band region by isolated ferric heme+ and heme+(histidine) in vacuo

Wyer

Nielsen

2010

The Journal of Chemical Physics

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Absorption by heme proteins is determined by the heme microenvironment that is often vacuumlike (hydrophobic pocket). Here we provide absorption spectra in the Q-band region of isolated ferric heme(+) and heme(+)(histidine) ions in vacuo to be used as references in protein biospectroscopy. Ions were photoexcited in an electrostatic storage ring and their decay monitored in time. Both ions display a triple band structure with maxima at 500, 518, and 530 nm. Previous attempts to study four-coordinate Fe(III)-heme(+) were hampered by the strong affinity of Fe(3+) for water and anions. Absorption at higher wavelengths is also measured, which is ascribed to charge-transfer transitions from the porphyrin to the iron. Finally, our data serve to benchmark theoretical calculations.

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Section: Introductionsupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Absorption in the Q-band region by isolated ferric heme+ and heme+(histidine) in vacuo

Wyer

Nielsen

2010

The Journal of Chemical Physics

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“…The MIKE spectrum obtained for the collisions between [PPϩH] ϩ cations (m/z 563) and helium is shown in Figure 1A and resembles previously published fragmentation spectra of similar porphyrin ions [26]. The dominant dissociation channel is loss of CH 2 COOH, which is the lowest-energy channel according to work by Charkin et al [27,28]. The other peaks are assigned to the loss of one or more side chains: CH 3 (15), CH 2 CH (27), COOH (45), CH 2 COOH (59), CH 2 CH 2 COOH (73) (mass).…”

Section: Resultsmentioning

confidence: 75%

Electron-capture—Induced dissociation of protoporphyrin IX ions

Bernigaud

Drenck

Huber

et al. 2008

J. Am. Soc. Mass Spectrom.

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Electron-capture induced dissociation of protoporphyrin cations and anions has been studied. The cations captured two electrons in two successive collisions and were converted to the corresponding even-electron anions. About one fifth of the ions lost a hydrogen atom to become radical anions but otherwise very little fragmentation was observed. The anions captured an electron to become dianions. No hydrogen loss occurred, and the only fragmentation channel observed was loss of CO2H, to give a doubly charged carbanion. Our results indicate that protoporphyrin ions are very efficient in accommodating one or even two electrons in the lowest unoccupied molecular orbital of the porphyrin macrocycle, and that electron capture induces only limited dissociation.

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“…The hybrid Becke-Lee-Yang-Parr (B3LYP) functional [21,22] and the 6-31 G(d) basis set were used for complete geometry optimization without any symmetry constraint. The level has been proved suitable for geometry optimization of iron porphyrins [23][24][25][26][27][28][29]. The following frequency analysis revealed that all the structures obtained in this work had no imaginary vibration, indicating that the lowest energy structures for all of the complexes were truly local minima in the potential energy surfaces.…”

Section: Methodsmentioning

confidence: 90%

Substituent effects on geometric and electronic properties of iron tetraphenylporphyrin: a DFT investigation

She

et al. 2011

J Mol Model

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To investigate the effects of the substituents, substituent positions and axial chloride ligand on the geometric and electronic properties of the iron tetraphenylporphyrin (FeTPP), a series of the substituented iron tetraphenylporphyrins and their chlorides, FeT(o/p-R)PP and FeT(o/p-R)PPCl (R = -H, -Cl, -NO(2), -OH, -OCH(3)), were systematically calculated without any symmetry constraint by using DFT method. For geometric structure, the substituent position and axial Cl ligand change the configuration of the iron porphyrin obviously. The ortho-substituents prefer making the phenyls perpendicular to the porphyrin ring; the axial chloride draws the central Fe ion ~0.500 Å out of the porphyrin plane toward the ligand. With regard to electronic properties, it is found that E(LUMO) could be related to the catalytic activity. The electron-withdrawing group always lowers the energies of both frontier orbitals, while the electron-donating one heightens them simultaneously, but they affect the E(HOMO) and E(LUMO) in the same sequence, -NO(2) < -Cl < -H < -OH < -OCH(3). The substituent effects on the central Fe ion were explored by calculating NBO charge distribution, spin density and natural electron configuration.

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Fragmentation of heme and hemin+ with sequential loss of carboxymethyl groups: A DFT and mass-spectrometry study

Cited by 37 publications

References 14 publications

Absorption in the Q-band region by isolated ferric heme+ and heme+(histidine) in vacuo

Absorption in the Q-band region by isolated ferric heme+ and heme+(histidine) in vacuo

Electron-capture—Induced dissociation of protoporphyrin IX ions

Substituent effects on geometric and electronic properties of iron tetraphenylporphyrin: a DFT investigation

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