Vibrational dynamics of thiocyanate and selenocyanate bound to horse heart myoglobin

Michał Maj, Younjun Oh, Kwanghee Park, Jooyong Lee, Kyungwon Kwak, Minhaeng Cho

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The structure and vibrational dynamics of SCN- and SeCN-bound myoglobin have been investigated using polarization-controlled IR pump-probe measurements and quantum chemistry calculations. The complexes are found to be in low and high spin states, with the dominant contribution from the latter. In addition, the Mb:SCN high spin complex exhibits a doublet feature in the thiocyanate stretch IR absorption spectra, indicating two distinct molecular conformations around the heme pocket. The binding mode of the high spin complexes was assigned to occur through the nitrogen atom, contrary to the binding through the sulfur atom that was observed in myoglobin derived from Aplysia Limacina. The vibrational energy relaxation process has been found to occur substantially faster than those of free SCN- and SeCN- ions and neutral SCN- and SeCN-derivatized molecules reported previously. This supports the N-bound configurations of MbNCS and MbNCSe, because S- and Se-bound configurations are expected to have significantly long lifetimes due to the insulation effect by heavy bridge atom like S and Se in such IR probes. Nonetheless, even though their lifetimes are much shorter than those of corresponding free ions in water, the vibrational lifetimes determined for MbNCS and MbNCSe are still fairly long compared to those of azide and cyanide myoglobin systems studied before. Thus, thiocyanate and selenocyanate can be good local probes of local electrostatic environment in the heme pocket. The globin dependence on binding mode and vibrational dynamics is also discussed.

Original languageEnglish
Article number235104
JournalJournal of Chemical Physics
Volume140
Issue number23
DOIs
Publication statusPublished - 2014 Jun 21

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horses
myoglobin
Myoglobin
Heme
life (durability)
Atoms
probes
Ions
Quantum chemistry
Globins
Azides
quantum chemistry
cyanides
Relaxation processes
configurations
Sulfur
insulation
nitrogen atoms
atoms
Conformations

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Vibrational dynamics of thiocyanate and selenocyanate bound to horse heart myoglobin. / Maj, Michał; Oh, Younjun; Park, Kwanghee; Lee, Jooyong; Kwak, Kyungwon; Cho, Minhaeng.

In: Journal of Chemical Physics, Vol. 140, No. 23, 235104, 21.06.2014.

Research output: Contribution to journalArticle

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