000257062 001__ 257062
000257062 005__ 20190111220314.0
000257062 0247_ $$2doi$$a10.1039/C8CP03989E
000257062 037__ $$aARTICLE
000257062 245__ $$aIntrinsic structure of pentapeptide Leu-enkephalin: geometry optimization and validation by comparison of VSCF-PT2 calculations with cold ion spectroscopy
000257062 260__ $$c2018-09-07
000257062 269__ $$a2018-09-07
000257062 336__ $$aJournal Articles
000257062 520__ $$aThe intrinsic structure of an opioid peptide [Ala2, Leu5]-leucine enkephalin (ALE) has been investigated using first-principles based vibrational self-consistent field (VSCF) theory and cold ion spectroscopy. IR-UV double resonance spectroscopy revealed the presence of only one highly abundant conformer of the singly protonated ALE, isolated and cryogenically cooled in the gas phase. High-level quantum mechanical calculations of electronic structures in conjunction with a systematic conformational search allowed for finding a few low-energy candidate structures. In order to identify the observed structure, we computed vibrational spectra of the candidate structures and employed the theory at the semi-empirically scaled harmonic level and at the first-principles based anharmonic VSCF levels. The best match between the calculated “anharmonic” and the measured spectra appeared, indeed, for the most stable candidate. An average of two spectra calculated with different quantum mechanical potentials is proposed for the best match with experiment. The match thus validates the calculated intrinsic structure of ALE and demonstrates the predictive power of first-principles theory for solving structures of such large molecules.
000257062 536__ $$aFNS$$c200020_159918
000257062 700__ $$aTapta Kanchan Roy
000257062 700__ $$aKopysov, Vladimir$$0246389
000257062 700__ $$aPereverzev, Aleksandr$$0247619
000257062 700__ $$aŠebek, Jiří
000257062 700__ $$aGerber, R. Benny
000257062 700__ $$aBoyarkine, Oleg$$0242817
000257062 773__ $$tPhys. Chem. Chem. Phys.$$j20$$k18$$q24894-24901
000257062 8560_ $$foleg.boiarkin@epfl.ch
000257062 909C0 $$pLCPM$$mthomas.rizzo@epfl.ch$$0252096$$zBorel, Alain$$xU10106
000257062 909CO $$pSB$$particle$$ooai:infoscience.epfl.ch:257062
000257062 960__ $$aoleg.boiarkin@epfl.ch
000257062 961__ $$aalain.borel@epfl.ch
000257062 973__ $$aEPFL$$sPUBLISHED$$rREVIEWED
000257062 980__ $$aARTICLE
000257062 981__ $$aoverwrite