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Signs of heteronuclear spin–spin coupling constants in 15 N‐acetamide
Author(s) -
De Marco Antonio,
Llinás Miguel
Publication year - 1979
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270120804
Subject(s) - heteronuclear molecule , coupling constant , chemistry , resonance (particle physics) , nuclear magnetic resonance , spectral line , acetamide , crystallography , physics , molecular physics , nuclear magnetic resonance spectroscopy , stereochemistry , atomic physics , quantum mechanics , organic chemistry
Abstract By using digital deconvolution to improve spectral resolution, earlier NMR studies on 15 N‐enriched acetamide have been revised and extended to determine the signs of the heteronuclear spin‐spin coupling constants. 1 J ( 13 CO 15 N), 2 J ( 13 CH 3 15 N) and 3 J (C 1 H 3 15 N) are negative while 3 J ( 1 H 13 CH 3 )>0. The results, interpreted on the basis of the ‘selective decoupling’ formalism, were confirmed by computer simulation of the double resonance spectra. It is shown that 2 J ( 1 H‐α 13 CO) is significantly larger than 2 J ( 1 H N 13 CO). Thus, jointly with { 1 H‐β}‐ 13 C′ double resonance experiments, { 1 H‐α}‐ 13 C′ experiments ought to be most helpful when assigning peptide group carbonyl resonances. The study provides valuable information for the interpretation of heteronuclear coupling constants in polypeptides.