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

Valat, P.; Alpert, Bernard

doi:10.1155/lc.5.173

Cited by 7 publications

(1 citation statement)

References 2 publications

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“…With this approach, the kinetic constant of the Stern-Volmer relation reflects the structural and dynamic protein constraints which favor or inhibit the random-walk mechanism of the oxygen molecules through the different domains. In this case, the backbone which occur on a very long time scale (> 5 ns) [19]. In the heme vicinity, unbound oxygen molecules have been detected in hemoglobin after picosecond irradiation [20].…”

Section: Discussionmentioning

confidence: 99%

Fluctuation domains in myoglobin

Albani

Alpert

1987

European Journal of Biochemistry

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The dynamics of two domains in the myoglobin molecule, close to the heme and inside the protein medium including the surface, are investigated through the study of the fluorescence oxygen quenchng of two probes imbedded in the heme pocket: zinc protoporphyrin IX (with a fluorescence lifetime of 2.1 ns) and metal-free protoporphyrin IX (with a fluorescence lifetime of 17.8 ns).The dynamic aspect of proteins has been well established in the last few years. Fluorescence quenching methodologies have been particularly important in t h s area (see [l] for a review). A detailed multifrequency phase and modulation study of the diffusion of oxygen in protoporphyrin IX adducts of hemoglobin and myoglobin has been published [2]. The data were analyzed in terms of a model which takes into account the rate of acquisition of quencher by the protein, the diffusional rate of quencher in the protein interior and the rate of exit of quencher from the protein [3]. However, in those studies the calculated rate of migration of quencher through the protein interior assumed isotropic diffusion and hence represented an average value. To address the question of anisotropic diffusion in the protein interior, i. e. varying diffusion rates in different protein domains, we have prepared the zinc protoporphyrin IX adduct of myoglobin. The rationale for this approach is that the shorter fluorescence lifetime of the zinc adduct (w 2 ns) compared to the metalfree adduct ( % 18 ns) would allow us to probe a region closer to the heme pocket. We report here for the first time results of oxygen quenching experiments on horse heart myoglobin labelled with these two probes. MATERIALS AND METHODS PreparationsHorse heart myoglobin was purchased from Sigma. The porphyrins were obtained from Porphyrin Products Inc. MbdesFe (myoglobin without iron) and MbFe + Zn (myoglobin in which the heme iron has been replaced by a zinc atom) were prepared by the procedure described previously for MbdesFe [2]. Incorporation of the porphyrins in the heme pocket of myoglobin was controlled by comparing the MbdesFe and absorption and emission spectra to those of porphyrins dissolved in different solvents (Tables 1 and 2). The quality and the homogeneity of the globin-porphyrins were confirmed by the homogeneous fluorescence lifetime of the first emission peak of the incorporated porphyrin in the All experiments were carried out in aqueous solvent at pH 7 with protein concentration near 3 pM for both proteins. Concentrations were determined spectrophotometrically using absorption coefficients of 122 mM-' cm-' at 427 nm for MbFe + Zn [5] and of 12.6 mM-' cm-I at 506 nm for t61. MbdesFe Absorbance and fluorescence spectraAbsorbance data were obtained with a Perkin-Elmer Lambda 5 UV/VIS spectrophotometer using 1 -cm-pathlength cuvettes. Technical fluorescence spectra were obtained with a Perkin-Elmer LS-5 spectrofluorometer. The bandwidths used for excitation and emission were 10 nm. Optical pathlengths of 1 cm and 0.4 cm were used for the mission and excitation wavelengths...

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Section: Discussionmentioning

confidence: 99%

Fluctuation domains in myoglobin

Albani

Alpert

1987

European Journal of Biochemistry

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Protein Fluctuations and Hemeprotein Affinity for Ligand

Alpert

1986

Structure and Dynamics of Nucleic Acids, Proteins, and Membranes

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Local changes in arterial oxygen saturation induced by visible and near-infrared light radiation

et al. 2015

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In this study, we investigate the efficiency of laser radiation on oxyhemoglobin (HbO2) rate in blood vessels and its wavelength dependence. The results of in vivo experimental measurements of the laser-induced photodissociation of HbO2 in cutaneous blood vessels in the visible and near-infrared (IR) spectral range are presented. Arterial oxygen saturation (SpO2) was measured by a method of fingertip pulse oximetry, which is based on the measurement of the modulated pulse wave of the blood. The light irradiating the finger was provided by corresponding light-emitting diodes (LED) at 15 wavelengths in the 400-940 nm spectrum range. Statistical results with a value of p < 0.05 were viewed as being significant for all volunteers. The results show that there is a decrease in SpO2 in the blood under the influence of the transcutaneous laser irradiation. Three maxima in the spectral range (530, 600, and 850 nm) are revealed, wherein decrease in the relative concentration of SpO2 reaches 5 % ± 0.5 %. Near-IR radiation plays a dominant role in absorption of laser radiation by oxyhemoglobin in deeper layers of tissue blood vessels. The obtained data correlate with the processes of light propagation in biological tissue. The observed reduction in SpO2 indicates the process of photodissociation of HbO2 in vivo and may result in local increase in O2 in the tissue. Such laser-induced enrichment of tissue oxygenation can be used in phototherapy of pathologies, where the elimination of local tissue hypoxia is critical.

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

Cited by 7 publications

References 2 publications

Fluctuation domains in myoglobin

Fluctuation domains in myoglobin

Protein Fluctuations and Hemeprotein Affinity for Ligand

Local changes in arterial oxygen saturation induced by visible and near-infrared light radiation

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