A theoretical study on the electronic structure of PYP chromophore in low barrier hydrogen bonding model

Abstract

Yamaguchi et al. have recently identified positions of hydrogen and deuterium atoms in photoactive yellow protein (PYP) using high-resolution neutron scattering. They reported that the hydrogen bond between the PYP chromophore and Glu46 was not a short ionic hydrogen bond (SIHB) but a low barrier hydrogen bond (LBHB). Furthermore, it was suggested that Arg52 close to the chromophore was deprotonated. In the present study, we investigate the electronic structure of the chromophore in PYP under the condition of protonated or deprotonated Arg52. By analyzing the potential energy curve along the proton migration between Glu46 and the chromophore, we find that a LBHB can be seen only when Arg52 is deprotonated.