Thermodynamic origin of cis/trans isomers of a proline-containing beta-turn model dipeptide in aqueous solution: A combined variable temperature H-1-NMR, two-dimensional H-1,H-1 gradient enhanced nuclear Overhauser effect spectroscopy (NOESY), one-dimensional steady-state intermolecular C-13,H-1 NOE, and molecular dynamics study

 
This item is provided by the institution :

Repository :
Repository of UOI Olympias
see the original item page
in the repository's web site and access all digital files if the item*
share




2000 (EN)

Thermodynamic origin of cis/trans isomers of a proline-containing beta-turn model dipeptide in aqueous solution: A combined variable temperature H-1-NMR, two-dimensional H-1,H-1 gradient enhanced nuclear Overhauser effect spectroscopy (NOESY), one-dimensional steady-state intermolecular C-13,H-1 NOE, and molecular dynamics study (EN)

Troganis, A. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Troganis, A. (EN)

(H2O) C-13, H-1 NOE indicates that the water accessibility of the acetyl carbonyl carbons is nearly the same for both isomers. This is consistent with rapid fluctuations of the conformational ensemble and the absence of a highly shielded acetyl oxygen from the bulk solvent. Variable temperature H-1-nmr studies of the cis/trans conformational equilibrium indicate that the trans form is enthalpically favored (Delta H degrees = -5.14 KJ mole(-1)) and entropically (Delta S degrees = -5.47 J . K-1 mole(-1)) disfavored relative to the cis form. This demonstrates that, in the absence of strongly stabilizing sequence-specific interresidue interactions involving side chains and/or charged terminal groups, the thermodynamic difference of the cis/trans isomers is due to the combined effect of intramolecular and intermolecular (hydration) induced conformational changes. (C) 2000 John Wiley & Sons, Inc. (EN)

hydration (EN)


Biopolymers (EN)

English

2000


Wiley-Blackwell (EN)




*Institutions are responsible for keeping their URLs functional (digital file, item page in repository site)