Isolated Gramicidin Peptides Probed by IR Spectroscopy

0435209 - ÚOCHB 2015 RIV DE eng J - Journal Article
Rijs, A. M. - Kabeláč, Martin - Abo-Riziq, A. - Hobza, Pavel - de Vries, M. S.
Isolated Gramicidin Peptides Probed by IR Spectroscopy.
ChemPhysChem. Roč. 12, č. 10 (2011), s. 1816-1821. ISSN 1439-4235. E-ISSN 1439-7641
R&D Projects: GA MŠMT LC512; GA AV ČR IAA400550808
Institutional research plan: CEZ:AV0Z40550506
Keywords : density functional calculations * gramicidin * IR spectroscopy * protein folding
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.412, year: 2011

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.
Permanent Link: http://hdl.handle.net/11104/0239124