Kinetics of the E46Q mutant of photoactive yellow protein investigated by transient grating spectroscopy

• DOI: 10.1016/j.cplett.2017.03.018
• Publication Date: 2017-03-08T13:46:07Z
• Authors: Cheolhee Yang; Tae Wu Kim; Youngmin Kim; Jungkweon Choi; Sang Jin Lee; Hyotcherl Ihee
• Keywords: 0301 basic medicine; 03 medical and health sciences

Abstract To elucidate the role of internal proton transfer in the photodynamics of photoactive yellow protein (PYP), the photocycle of the Glu46Gln mutant of PYP (E46Q-PYP) is investigated by transient grating (TG) spectroscopy. Compared with wild-type PYP (wt-PYP), the first spectrally blue-shifted intermediate of E46Q-PYP is formed more slowly, which is consistent with the absence of direct protonation from Glu46 residue, if the parallel kinetic model for wt-PYP is invoked. The smaller conformational change in E46Q-PYP, as manifested by the smaller change in the diffusion coefficient, mainly arises from the relatively larger volume of the ground state E46Q-PYP than wt-PYP rather than from the smaller volume of the pB state.