O-17 NMR studies of the solvation state of cis/trans isomers of amides and model protected peptides
| dc.contributor.author | Gerothanassis, I. P. | en |
| dc.contributor.author | Vakka, C. | en |
| dc.contributor.author | Troganis, A. | en |
| dc.date.accessioned | 2015-11-24T16:35:18Z | |
| dc.date.available | 2015-11-24T16:35:18Z | |
| dc.identifier.issn | 1064-1866 | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/7927 | |
| dc.rights | Default Licence | - |
| dc.subject | nuclear magnetic-resonance | en |
| dc.subject | acetyl-l-proline | en |
| dc.subject | chemical-shifts | en |
| dc.subject | aqueous-solution | en |
| dc.subject | spectroscopy | en |
| dc.subject | water | en |
| dc.subject | turns | en |
| dc.subject | bond | en |
| dc.subject | cis | en |
| dc.subject | conformation | en |
| dc.title | O-17 NMR studies of the solvation state of cis/trans isomers of amides and model protected peptides | en |
| heal.abstract | O-17 shielding constants have been utilized to investigate solvation differences of the cis/trans isomers of N-methylformamide (NMF), N-ethylformamide (NEF), and tert-butylformamide (TBF) in a variety of solvents with particular emphasis on aqueous solution. Comparisons are also made with protected peptides of the formulas CH3CO-YOH, CH3CO-Y-NHR (Y = Pro, Sar), and CH3CO-Y-Z-NHR (Y = Pro; Z = D-Ala) selectively enriched in O-17 at the acetyl oxygen atom. Hydration at the amide oxygen induces large and specific modifications of the O-17 shielding constants, which are practically the same for the cis and trans isomers of NMF, NEF, and the protected peptides. For tert-butylformamide, the strong deshielding of the trans isomer compared to that of the cis isomer may be attributed to an out-of-plane (torsion-angle) deformation of the amide bond and/or a significant reduction of solvation of the trans isomer due to steric inhibition of the bulky tert-butyl group. Good linear correlation between delta(O-17) of amides and delta(O-17) of acetone was found for different solvents which have varying dielectric constants and solvation abilities. Sum-over-states calculations, within the solvaton model, underestimate effects of the dielectric constant of the medium on O-17 shielding, while finite-perturbation-theory calculations give good agreement with the experiment. (C) 1996 Academic Press, Inc. | en |
| heal.access | campus | - |
| heal.fullTextAvailability | TRUE | - |
| heal.identifier.secondary | <Go to ISI>://A1996UQ67800002 | - |
| heal.journalName | Journal of Magnetic Resonance Series B | en |
| heal.journalType | peer reviewed | - |
| heal.language | en | - |
| heal.publicationDate | 1996 | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών | el |
| heal.type | journalArticle | - |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.type.en | Journal article | en |
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