Deuteration of the protein molecules at the carbon sites brings some change in the isotropic chemical shifts, which has been reported previously. Although the NMR studies have shown many applications towards proteins molecules, isotope effect on chemical shift has been rarely explored. Consequently, we were inclined to computationally study the isotope effects on the chemical shifts on the backbone nuclei in Proteins based upon experimental report. We performed two different computational approaches viz. MP2/6-31+G(d,p) and B3LYP/6-311+G(d,p) first to calculate a few model geometries containing peptide framework and then computed the NMR data at the B3LYP/6-311+G(d,p) on the optimized geometries. We used anharmonic procedure to compute the vibrationally averaged geometries with H and D isotopes. To compare the experimental observations, we acquired a number of conformations by a rotation of psi-i dihedral angle. Our computational results clearly show changes in the chemical shifts of 13C and 15N although the trend in these istotropic shifts do not reflect the experimental data corresponding to backbone nuclie's in protein.

Effect of deuterium isotope on the chemical shifts in proteins

245th National Meeting (2013)

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