Role of atomic contacts in vibrational energy transfer in myoglobin

摘要

Crystallographic structure of wild-type sperm whale Mb (Protein Data Bank entry 1BZ6). The protein backbone structure is represented as a gray ribbon superimposed with a gray surface. Orange spheres represent atoms in the heme group. Gray spheres are the α-carbons in two intrinsic Trp residues, Trp7 and Trp14. Blue, red, and green spheres indicate α-carbons of amino acid residues at 43, 68, and 89th positions, respectively, each of which was substituted to the probe Trp residue. Structures around the heme group in the Mb mutants; F43W (left, Protein Data Bank entry 2E2Y), V68W (middle, Protein Data Bank entry 2OH9), and L89W (right, Protein Data Bank entry 1CH3). Orange and cyan spheres of each panel represent the heme group and the probe Trp residue, respectively. Picosecond time-resolved anti-Stokes UVRR spectra of F43W (left), V68W (middle), and L89W (right), which were obtained using the 405 nm pump and 230 nm probe pulses. In each panel, the top trace is the anti-Stokes UVRR spectrum without pump-pulse irradiation. The other traces are time-resolved difference spectra generated by subtracting the spectrum without pump-pulse irradiation from each time-resolved spectrum. The self-absorption effect was corrected using the intensity of the sulfate ion band at 983 cm indicated as an asterisk. The accumulation time for obtaining each spectrum was 82 min. Temporal evolutions of photoinduced intensity changes in the anti-Stokes W18 bands for Trp43 (blue squares), Trp68 (red circles), and Trp89 (green triangles). Solid lines are the best fits to the Eq. ( ). Model to analyze the temporal evolutions of anti-Stokes UVRR intensities. (Adapted with permission from Kondoh et al. ( ) J Phys Chem Lett 7:1950–1954, Copyright 2016 American Chemical Society)