Conformational dependence of the vicinal proton coupling constant for the C^αC^β bond in peptides

Abstract

Abstract We use the nmr data concerning the C α HC β H fragment in eight peptides with rigid side chains to parametrize a Karplus correlation between the vicinal proton J αβ coupling constant and the dihedral angle θ. When considering molecules containing the fragment C α H α C β H β H β′ , the three‐dimensional structure of the model peptides does not need to be known with accurate precision, since each set of J αβ and J αβ′ coupling constants is then related to the coefficients of the Karplus equation. A good correlation is observed with the Karplus equation, which is in substantial agreement with the J αβ coupling constants reported for rigid as well as rotating C α C β bonds in peptides.