[The flash-photolysis study of recombination of hemoproteins with carbon monoxide at low temperatures].
The hemoproteins (sperm whale myoglobin, hemoglobin from larvae of Chironomus thummi thummi, bovine hemoglobin) were studied in viscous solvents (saturated sucrose solution, glycerol and water-glycerol solutions) in the temperature range +50 divided by -100 degrees C. At low temperatures the three-phase kinetics of Mb recombination with CO was observed. The velocities of two "fast" reactions did not depend on ligand concentration. This fact indicates that they are due to a so called cage-effect. The formation of the cage is caused apparently by a local change of the solvent state in the heme region. To explain the biphasic "cage" kinetics it has been assumed that during some time after photodissociation myoglobin remains in the "ligand-bound" conformation and reacts with CO faster than the "normal" myoglobin. For other hemoproteins the "cage-effect" was not observed. For all the studied hemoproteins the quantum yield of photodissociation decreased as the temperature decreased. The decrease of quantum yield can be described by the Arrenius law. The rates of the decrease of quantum yield differ for different proteins.
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004175:Diptera; D006454:Hemoglobins; D007700:Kinetics; D007814:Larva; D008024:Ligands; D009211:Myoglobin; D010782:Photolysis; D011485:Protein Binding; D011487:Protein Conformation; D014907:Whales
D006454:Hemoglobins; D008024:Ligands; D009211:Myoglobin
Issledovanie kinetiki rekombinatsii gemoproteinov s okis'iu ugleroda pri nizkikh temperaturakh metodom impul'snogo fotoliza