Vibrational analysis on the revised potential energy curve of the low-barrier hydrogen bond in photoactive yellow protein

Publication date: Available online 31 October 2015 Source:Computational and Structural Biotechnology Journal Author(s): Yusuke Kanematsu, Masanori Tachikawa Photoactive yellow protein (PYP) has a characteristic hydrogen bond (H bond) between p-coumaric acid chromophore and Glu46, whose OH bond length has been observed to be 1.21Å by the neutron diffraction technique [Proc. Natl. Acad. Sci. 106, 440–4]. Although it has been expected that such a drastic elongation of the OH bond could be caused by the quantum effect of the hydrogen nucleus, previous theoretical computations including the nuclear quantum effect have so far underestimated the bond length by more than 0.07Å. To elucidate the origin of the difference, we performed a vibrational analysis of the H bond on potential energy curve with O…O distance of 2.47Å on the equilibrium structure, and that with O…O distance of 2.56Å on the experimental crystal structure. While the vibrationally averaged OH bond length for equilibrium structure was underestimated, crystal structure lengths were in reasonable agreement with the corresponding experimental values. The elongation of the O…O distance by the quantum mechanical or thermal fluctuation would be indispensable for the formation of a low-barrier hydrogen bond in PYP.

Source: Computational and Structural Biotechnology Journal - November 13, 2015 Category: Biotechnology Source Type: research