TY - JOUR
T1 - Isolated gramicidin peptides probed by IR spectroscopy
AU - Rijs, Anouk M.
AU - Kabeláč, Martin
AU - Abo-Riziq, Ali
AU - Hobza, Pavel
AU - De Vries, Mattanjah S.
PY - 2011/7/11
Y1 - 2011/7/11
N2 - We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm-1 to 1800 cm-1 and the 2700 to 3750 cm-1 region, allow structural analysis. By studying this broad IR range, various local intramolecular interactions are probed, and complementary IR modes can be accessed. Ab initio quantum chemical calculations are used to support the interpretation of the experimental IR spectra. The comparison of the calculated frequencies with the experimental IR spectrum probed via the strong infrared absorptions of all the amide groups (NH stretch, C=O stretch and NH bend), shows evidence for a helical structure in the gas phase, which is similar to that in the condensed phase. Additionally, we show that to improve the spectral resolution when studying large neutral molecular structures of the size of gramicidin, the use of heavier carrier gas could be advantageous. Through the (IR) looking glass: IR spectra of isolated neutral gramicidin are obtained in the mid and near-IR spectral range (see picture) and compared with high-level quantum chemical calculations. The gas-phase spectra reveal a helical structure, similar to that in the condensed phase.
AB - We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm-1 to 1800 cm-1 and the 2700 to 3750 cm-1 region, allow structural analysis. By studying this broad IR range, various local intramolecular interactions are probed, and complementary IR modes can be accessed. Ab initio quantum chemical calculations are used to support the interpretation of the experimental IR spectra. The comparison of the calculated frequencies with the experimental IR spectrum probed via the strong infrared absorptions of all the amide groups (NH stretch, C=O stretch and NH bend), shows evidence for a helical structure in the gas phase, which is similar to that in the condensed phase. Additionally, we show that to improve the spectral resolution when studying large neutral molecular structures of the size of gramicidin, the use of heavier carrier gas could be advantageous. Through the (IR) looking glass: IR spectra of isolated neutral gramicidin are obtained in the mid and near-IR spectral range (see picture) and compared with high-level quantum chemical calculations. The gas-phase spectra reveal a helical structure, similar to that in the condensed phase.
KW - density functional calculations
KW - gramicidin
KW - IR spectroscopy
KW - protein folding
KW - structural analysis
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U2 - 10.1002/cphc.201100212
DO - 10.1002/cphc.201100212
M3 - Article
AN - SCOPUS:79959781795
SN - 1439-4235
VL - 12
SP - 1816
EP - 1821
JO - ChemPhysChem
JF - ChemPhysChem
IS - 10
ER -