Electronic Relaxation and Oxygen Recombination Processes in Photodissociated Oxyhemoglobin After Picosecond Flash Photolysis

Valat, P.; Tourbez, H.; Alpert, Bernard

doi:10.1155/lc.1.45

Cited by 12 publications

(11 citation statements)

References 5 publications

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“…for HbO2 photodissociation (see Table 1). From our kinetic data, 23 in a 30 ps photolysis experiment less of 2% of O2 molecules can recombine with the iron. The almost total absence of 02 geminate recombination during the picosecond pulse and the high value of the Q.Y.…”

Section: Photolysis Pulse-width Effect On the Quantum Yield Valuementioning

confidence: 79%

“…Since the O.D. change of picosecond photodeligated and stable deoxyhemoglobin species has the maximum amplitude at 576 nm and 100 ps after the laser irradiation, 23 analysis ofthe effect ofthe energy of photodissociating pulse on the dissociation rate was performed at this wavelength and 100 ps after the photodissociating pulse. Compare to the data obtained during the 30 ps photodissociating pulse, these conditions increase about 20% the precision of the photolysis observation.…”

Section: Methodsmentioning

confidence: 99%

“…Using 30ps fwhm pulse we have shown that only 65% of the deligated 02 molecules recombined with the iron within 5 ns and this recombination followed a single exponential kinetic law. 23 Using laser pulses of 1.5 ns fwhm, 6 one can see the above exponential term of 02 geminate recombination followed by a second 02 geminate phase lasting 100 ns. This second term was found to obey x/7 kinetics.…”

Section: Protein Dynamics and Quantum Yieldmentioning

confidence: 98%

“…variations at some wavelengths indicated that photodissociation was about 25% incomplete. 23 At this high photodissociation level, the picosecond optical density would have to be corrected for a fraction of deoxy hemoglobin (Hb) which would absorb some excitation photon. Care should be taken to avoid these effects in picosecond ligand photodissociation.…”

Section: Photodissociationmentioning

confidence: 99%

“…The present study represents an extension of previously reported experiments on the oxygen geminate recombination in hemoglobin. 23 In this case we have focused our efforts on the direct determination of the Q.Y. of the oxyhemoglobin (HbO2) picosecond photodissociation.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Yield of ThirtyPicosecond OxyhemoglobinPhotodissociation. Effect ofProtein Fluctuations on theQuantum Yield Values

Valat

Alpert

1985

Laser Chemistry

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We have measured the absolute quantum yield of the oxyhemoglobin photodissociation with a 30 ps laser pulse excitation. We report that oxyhemoglobin dissociates with the same yield as carboxymyoglobin under photostationary conditions. Based on the picosecond and nanosecond experimental data, we show that oxygen geminate recombination is responsible for the low quantum yield values of oxyhemoglobin photodissociation measured with longer photolysis flashes. Kinetic data suggest that two geminate regimes which successively appear in oxygen recombination can be resolved. The first can be entirely attributed to the hemoglobin-iron chemical reactivity and, the second to the action of protein fluctuations.

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Section: Photolysis Pulse-width Effect On the Quantum Yield Valuementioning

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Section: Protein Dynamics and Quantum Yieldmentioning

confidence: 98%

Section: Photodissociationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantum Yield of ThirtyPicosecond OxyhemoglobinPhotodissociation. Effect ofProtein Fluctuations on theQuantum Yield Values

Valat

Alpert

1985

Laser Chemistry

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Do the hemeproteins behave as a dissipative structure?

Alpert¹,

Tilly²,

Pin³

et al. 1996

Int. J. Quantum Chem.

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Continuing the search for a broader interpretation of hemeprotein behavior, we give preliminary results showing that there are electric and dynamic couplings between the heme group and amino acid residues within the protein matrix. EPR and X-ray absorption spectroscopy studies on azidometmyoglobin show that both magnetic and geometric properties of Fe-N, evolve in the same nonlinear way as pH is increased and are tightly correlated to the strains on the helical segments of the protein. Flash photolysis of carbon monoxide hemoglobin, in the presence of ethanol or formamide, allows the study of cosolvent effects on geminate and nongeminate recombinations of the CO ligand trapped within the protein matrix. Data clearly show that cosolvents alter the statistic fluctuations of the protein, as well as the ligand partition between different protein matrix domains. From these studies, it is concluded that alterations occurring at particular sites give way to global protein perturbations. Then, each perturbated protein domain-binding site included-evolves with its own sensitivity to a new metastable state of the protein. The amplification of the initial perturbation which-instead of regressing-progressively propagates through the whole macromolecule is typical of a dissipative structure in the Prigogine sense. Biological properties of hemeproteins largely involve the surrounding solvent, via permanent or temporary exchanges of water molecules, protons, and small ligands. These fluxes along with their entropic corollary are not quite compatible with a conservative system. These works present the current trends developed in our laboratory in association with the European network "The Dynamics of Protein Structure." In this framework, our laboratory collaborates with Dr. W. Doster and T. Kleinert (Munich, Germany) for the CO recombination studies in hemoglobin and with Dr.

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