Preparation of ruthenium(II) and ruthenium(III) myoglobin and the reaction of dioxygen, and carbon monoxide, with ruthenium(II) myoglobin.

Ruthenium myoglobins have been prepared by the reconstitution of horse heart apomyoglobin with either ruthenium(II) or ruthenium(III) mesoporphyrin IX (MpIX) derivatives. The ruthenium(II) and -(III) myo globins (RuMb and RuMb+, respectively) contain one ruthenium porphyrin/heme binding site; the species are readily interconverted using dithionite for reduction and bromine for oxidation. RuMb binds carbon monoxide to give the known carbonyl complex. Reversible oxygenation occurs readily with protein-free RuII(MpIX) species in dimethylformamide, but RuMb in phosphate buffer is irreversibly oxidized by dioxygen to give RuMb+ via an outer sphere electron transfer mechanism.