6 research outputs found
Molecular oxygen binding with α and β subunits within the R quaternary state of human hemoglobin in solutions and porous sol–gel matrices
The kinetics of molecular oxygen migration in the isolated α chains of human hemoglobin as revealed by molecular dynamics simulations and laser kinetic spectroscopy
Mutual effects of proton and sodium chloride on oxygenation of liganded human hemoglobin
Photosensitized Singlet Oxygen Luminescence from the Protein Matrix of Zn-Substituted Myoglobin
A nanosecond laser near-infrared
spectrometer was used to study
singlet oxygen (<sup>1</sup>O<sub>2</sub>) emission in a protein matrix.
Myoglobin in which the intact heme is substituted by Zn-protoporphyrin
IX (ZnPP) was employed. Every collision of ground state molecular
oxygen with ZnPP in the excited triplet state results in <sup>1</sup>O<sub>2</sub> generation within the protein matrix. The quantum yield
of <sup>1</sup>O<sub>2</sub> generation was found to be equal to 0.9
± 0.1. On the average, six from every 10 <sup>1</sup>O<sub>2</sub> molecules succeed in escaping from the protein matrix into the solvent.
A kinetic model for <sup>1</sup>O<sub>2</sub> generation within the
protein matrix and for a subsequent <sup>1</sup>O<sub>2</sub> deactivation
was introduced and discussed. Rate constants for radiative and nonradiative <sup>1</sup>O<sub>2</sub> deactivation within the protein were determined.
The first-order radiative rate constant for <sup>1</sup>O<sub>2</sub> deactivation within the protein was found to be 8.1 ± 1.3 times
larger than the one in aqueous solutions, indicating the strong influence
of the protein matrix on the radiative <sup>1</sup>O<sub>2</sub> deactivation.
Collisions of singlet oxygen with each protein amino acid and ZnPP
were assumed to contribute independently to the observed radiative
as well as nonradiative rate constants