Using single turnover experiments, we have been able to probe the auto-reduction mechanism of the high-valent iron species in horse heart myoglobin (Mb). By varying the pH and temperature of the reaction and utilizing solvent kinetic Isotope effects (sKIE), we were able to uncover an additional intermediate between Mb Compound II (Cpd II) decay and protein oxidized Ferric Mb formation. Formation of this intermediate is pH sensitive, supporting previous hypothesis of an altered Mb Ferryl at low pH which is currently thought to be a hydrogen bonding interaction between the distal histidine and the ferryl oxo. Our pH studies indicate that the formation of this ferryl oxo hydrogen bonding intermediate appears to be necessary for the successive electron transfer event.

Probing the pH sensitivity in the mechanism of myoglobin compound II auto-reduction

2019 Spring National Meeting

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