Chemical shift in proteins

From NMR Wiki

Temperature dependence

Amide and Hα chemical shift of proteins was shown to change linearly in the range from -4 ^oC to about 15^o below the melting temperature or 94 ^oC [1]. Chemical shifts of amide protons are typically decreasing (moving upfield), while those of Hα atoms might be either increasing or decreasing. The range of temperature coefficients for the HN protons is 2-3 times wider then that of Hα protons.

Systematic decrease of HN proton chemical shift with temperature is explained by lengthening of hydrogen bonds upon heating, where interaction of proton with the acceptor carbonyl groups is decreasing.

References

1. Baxter, NJ and Williamson, MP. Temperature dependence of 1 H chemical shifts in proteins. Journal of Biomolecular NMR 9(4):359--369, 1997. BibTeX [baxter97]