Hemerythrin's oxygen-binding reaction studied by laser photolysis

Area of Science:

• Biochemistry
• Photochemistry
• Protein dynamics

Background:

• Oxyhemerythrin contains a dioxygen-iron bond.
• The behavior of this bond under photodissociation is not fully understood.

Purpose of the Study:

• To investigate the photosensitivity of the dioxygen-iron bond in oxyhemerythrin.
• To determine the influence of solvent viscosity on the recombination kinetics after photodissociation.

Main Methods:

• Flash photolysis was used to induce photodissociation of the dioxygen-iron bond.
• Recombination kinetics were studied in solvents of varying viscosity (water and a glycerol/water mixture).

Main Results:

• The dioxygen-iron bond in oxyhemerythrin is photosensitive.
• Recombination in water (1 cP) is monophasic and second-order in oxygen concentration (k = 2.9 x 10(7) M-1 s-1).
• A concentration-dependent geminate recombination process was observed in a viscous glycerol/water mixture (180 cP).

Conclusions:

• Solvent viscosity significantly impacts the recombination dynamics of photodissociated oxyhemerythrin.
• Flash photolysis is a viable technique for studying this class of proteins.
• The findings provide insights into protein-ligand bond dynamics and solvent-protein interactions.