Geminate recombination of O2 and hemoglobin.
- 1 October 1980
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 77 (10) , 5606-5610
- https://doi.org/10.1073/pnas.77.10.5606
Abstract
The photolysis of [human] HbO2 and HbCO was studied by measuring transient absorption spectra in the Soret region after excitation with ps pulses at 530 nm. Dissociation occurred promptly in both cases, followed (for HbO2) by geminate recombination of .apprx. 40% of the photodissociated O2 with a lifetime of 200 .+-. 70 ps (25.degree. C). No recombination of Hb + CO was observed up to 1200 ps after photolysis. The HbO2 and HbCO photoproduct spectra were broader, weaker and red-shifted in comparison to the spectrum of stable Hb and Gibson''s fast-reacting form, Hb*. For HbO2 the spectrum was initially much broader to longer wavelengths but relaxed to a constant shape within 90 ps, whereas for HbCO there was no spectral evolution. The photophysics is analyzed by considering the effect of spin constraints and spin-orbit coupling and orbital correlation among the various electronic states of liganded and deoxy Hb. The small quantum yield of HbO2 dissociation is not primarily due to rebinding but rather to electronic relaxation to nonreactive states.This publication has 21 references indexed in Scilit:
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