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Direct calculation oftranshydrogen-bond 13C-15N 3-bond J-couplings in entire polyalanine α-helices. A density functional theory study.
Autorzy
Rok wydania
2007
Czasopismo
Journal of Physical Chemistry B
Numer woluminu
111
Strony
2398-2403
DOI
10.1021/jp064706c
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
We present the first trans-H-bond 13C−15N 3-bond J couplings calculated from entire neutral and protonated α-helical polyalanines. The neutral helices considered are those of the capped peptides, acetyl(Ala)NNH2, where N = 8, 16, 17, and 18, while the protonated peptides are the uncapped (Ala)17 protonated at three different positions. The calculated J values correlate well with O···H distances and somewhat less well with N···O distances, particularly if the terminal H-bonds are eliminated from the correlation. The J values calculated using the entire helix are about 6% lower in magnitude than those recently reported for H-bonding chains whose geometries were extracted from the same helices. Aqueous solvation favors protonation of the α-helix on the terminal COOH. Experimental measurements of the trans-H-bond 13C−15N 3-bond J couplings in acidic solution should be interpreted with this context.
Słowa kluczowe
Chemical calculations, Chemical structure, Coupling reactions, Peptides and proteins, Reaction mechanisms
Adres publiczny
https://doi.org/10.1021/jp064706c
Strona internetowa wydawcy
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