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Ultrafast Structural Fluctuations of Myoglobin‐Bound Thiocyanate and Selenocyanate Ions Measured with Two‐Dimensional Infrared Photon Echo Spectroscopy
Author(s) -
Maj Michał,
Kwak Kyungwon,
Cho Minhaeng
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201500606
Subject(s) - myoglobin , thiocyanate , chemistry , spectroscopy , infrared , ultrashort pulse , ion , infrared spectroscopy , photochemistry , analytical chemistry (journal) , inorganic chemistry , optics , organic chemistry , laser , physics , quantum mechanics
Structural dynamics within the distal cavity of myoglobin protein is investigated using 2D‐IR and IR pump–probe spectroscopy of the N≡C stretch modes of heme‐bound thiocyanate and selenocyanate ions. Although myoglobin‐bound thiocyanate group shows a doublet in its IR absorption spectrum, no cross peaks originating from chemical exchange between the two components are observed in the time‐resolved 2D IR spectra within the experimental time window. Frequency–frequency correlation functions of the two studied anionic ligands are obtained by means of a few different analysis approaches; these functions were then used to elucidate the differences in structural fluctuation around ligand, ligand–protein interactions, and the degree of structural heterogeneity within the hydrophobic pocket of these myoglobin complexes.