Quantitative Determination of Ala-Ala Conformer Ratios in Solution by Decomposition of Raman Optical Activity Spectra

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388963%3A_____%2F17%3A00480247" target="_blank" >RIV/61388963:_____/17:00480247 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/61989592:15310/17:73582186

Výsledek na webu

<a href="http://dx.doi.org/10.1021/acs.jpcb.7b07154" target="_blank" >http://dx.doi.org/10.1021/acs.jpcb.7b07154</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpcb.7b07154" target="_blank" >10.1021/acs.jpcb.7b07154</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Quantitative Determination of Ala-Ala Conformer Ratios in Solution by Decomposition of Raman Optical Activity Spectra

Popis výsledku v původním jazyce

Raman optical activity (ROA) spectroscopy combined with quantum-chemical simulations is a sensitive method to determine the absolute configuration and conformation of chiral molecules in solutions. However, the precision of this approach varies for different systems. In the present study, the reliability and numerical stability of decomposing experimental spectra into calculated subspectra is tested on the Ala-Ala dipeptide. Molecular dynamics (MD) snapshots of Ala-Ala/water clusters are averaged to account for solvent effects and molecular flexibility. Multiple experiments with protonated, zwitterionic, and deprotonated dipeptide forms and natural and d(2)- and d(8)-isotopically labeled dipeptides are used to verify the results and estimate the overall accuracy. Although the precision is still limited by experimental noise and computational error, a very close match between the observed and theoretical spectral shapes has been achieved. This enabled quantitative determination of conformer populations with a typical dispersion of 10%. The spectroscopy also demonstrated how the conformation depends on pH. The ROA results were more consistent than the Raman ones. Typically, the ROA analysis was more resistant to artifacts in the experiment, such as incomplete baseline subtraction. Conformer ratios predicted by MD agree fairly but not fully with the experimental ones. This indicates minor deficiencies in the Amber force field, particularly for the protonated dipeptide. Overall, the combination of ROA experiment and computational chemistry appears to be a robust tool providing deep insight into molecular structure.

Název v anglickém jazyce

Quantitative Determination of Ala-Ala Conformer Ratios in Solution by Decomposition of Raman Optical Activity Spectra

Popis výsledku anglicky

Raman optical activity (ROA) spectroscopy combined with quantum-chemical simulations is a sensitive method to determine the absolute configuration and conformation of chiral molecules in solutions. However, the precision of this approach varies for different systems. In the present study, the reliability and numerical stability of decomposing experimental spectra into calculated subspectra is tested on the Ala-Ala dipeptide. Molecular dynamics (MD) snapshots of Ala-Ala/water clusters are averaged to account for solvent effects and molecular flexibility. Multiple experiments with protonated, zwitterionic, and deprotonated dipeptide forms and natural and d(2)- and d(8)-isotopically labeled dipeptides are used to verify the results and estimate the overall accuracy. Although the precision is still limited by experimental noise and computational error, a very close match between the observed and theoretical spectral shapes has been achieved. This enabled quantitative determination of conformer populations with a typical dispersion of 10%. The spectroscopy also demonstrated how the conformation depends on pH. The ROA results were more consistent than the Raman ones. Typically, the ROA analysis was more resistant to artifacts in the experiment, such as incomplete baseline subtraction. Conformer ratios predicted by MD agree fairly but not fully with the experimental ones. This indicates minor deficiencies in the Amber force field, particularly for the protonated dipeptide. Overall, the combination of ROA experiment and computational chemistry appears to be a robust tool providing deep insight into molecular structure.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Physical Chemistry B

ISSN

1520-6106

e-ISSN

—

Svazek periodika

121

Číslo periodika v rámci svazku

38

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

9

Strana od-do

8956-8964

Kód UT WoS článku

000412150700009

EID výsledku v databázi Scopus

2-s2.0-85030462605