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Updated: May 9, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Porphyrin π-stacking in a heme protein scaffold tunes gas ligand affinity
Emily E Weinert1, Christine M Phillips-Piro, Michael A Marletta
1Department of Chemistry, Emory University, Atlanta, GA 30322, United States.
Abstract:
The role of π-stacking in controlling redox and ligand binding properties of porphyrins has been of interest for many years. The recent discovery of H-NOX domains has provided a model system to investigate the role of porphyrin π-stacking within a heme protein scaffold. Removal of a phenylalanine-porphyrin π-stack dramatically increased O2, NO, and CO affinities and caused changes in redox potential (~40mV) without any structural changes. These results suggest that small changes in redox potential affect ligand affinity and that π-stacking may provide a novel route to engineer heme protein properties for new functions.
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