# Conformational Dependence of Vicinal $^{13}C^{\prime}NC^{\alpha} H$ Coupling Constants in Peptides: A Dirac Cector Model Investigation

Mohanakrishnan, P and Easwaran, KRK (1979) Conformational Dependence of Vicinal $^{13}C^{\prime}NC^{\alpha} H$ Coupling Constants in Peptides: A Dirac Cector Model Investigation. In: Biopolymers, 18 (7). pp. 1769-1774.

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Theoretical calculations of the heteronuclear vicinal coupling constant $^3J(^{13}C^{\prime}NC^{\alpha} H$) in peptides have been carried out using the Dirac vector model. The results showed an angular dependence for this coupling constant, which can be expressed in the form $^3J (^{13}C^{\prime}NC^{\alpha} H) = A cos^2 \theta + B cos \theta + C$, where A, B, and C are constants and \theta is related to the torsional angle \phi of the peptide backbone. The results of the present calculations are in very good agreement with those obtained using finite perturbation theory at the INDO level of approximation.