Using single turnover experiments, we have been able to probe the proton transfers in the auto-reduction mechanism of the high-valent iron species in horse heart myoglobin (Mb). Using kinetic solvent isotope effects (sKIE) and proton inventories, we uncovered an unusual proton inventory effect for the auto-reduction reaction when the solution had a pD/pH of 5.0. The inventory displayed an inverted rate for auto-reduction which curve up at deuterium ratios around 50%. Analyzing the inventory can allow us to determine if multiple pathways or species, multiple fractionation factors, a mixture of solvent equilibrium isotope effects, or a combination of several of these factors is creating the highest rates at mixed ratios of water and deuterated water instead of pure water or pure deuterium oxide.

Exploring an unusual proton inventory curve seen in the low pD reaction of the compound II auto-reduction in horse heart myoglobin

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.