Membrane-mimicking surfaces modulate the heme pocket structure and oxygen affinity in myoglobin: A surface-enhanced...

In this study, we investigated how membrane-mimicking surfaces modulate the structure and oxygen affinity of myoglobin (Mb) using surface-enhanced resonance Raman spectroscopy under electrochemical control. Nanostructured silver electrodes functionalized with self-assembled monolayers of varying charge and composition were employed to model basic features of the outer mitochondrial membrane in a controlled fashion. Molecular dynamics simulations show that the interactions of Mb with these surfaces are mediated by lysine-rich domains in helix F and the CD region. These interactions induce subtle structural changes in Mb's heme pocket, of both the ferric and ferrous protein, that imply the loss of the proximal ligand, water and molecular oxygen, respectively. The fraction of ferrous OxyMb that retains the oxygen ligand in the biomimetic complexes exhibits spectral features consistent with a weakened Fe-O₂ bond and decreased O₂ affinity. Overall, our findings show that Mb's transient interaction with a mitochondrial membrane model facilitates O₂ release through fine structural modulation, providing a possible molecular basis for how such interactions might influence oxygen delivery in cells.