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Updated: Apr 24, 2026

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Spectroscopic evidence for a redox-controlled proton gate at tyrosine D in Photosystem II
Johannes Sjöholm1, Fikret Mamedov, Stenbjörn Styring
1Molecular Biomimetics, Department of Chemistry-Ångström Laboratory, Uppsala University , P.O. Box 523, SE-751 20 Uppsala, Sweden.
Abstract:
Tyrosine D (TyrD) is one of two well-studied redox active tyrosines in Photosystem II. TyrD shows redox kinetics much slower than that of its homologue, TyrZ, and is normally present as a stable deprotonated radical (TyrD(•)). We have used time-resolved continuous wave electron paramagnetic resonance and electron spin echo envelope modulation spectroscopy to show that deuterium exchangeable protons can access TyrD on a time scale that is much faster (50-100 times) than that previously observed. The time of H/D exchange is strongly dependent on the redox state of TyrD. This finding can be related to a change in position of a water molecule close to TyrD.
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