Chemical shift in proteins

From NMR Wiki

Article [1] is a good resource of references on the subject of chemical shift in proteins.

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.

Hydrogen-bound protons show smaller temperature coefficient of the chemical shift. Protons that are not hydrogen-bound to protein hydrogen bond acceptors show stronger temperature dependency of the chemical shift. 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. Due to restrictions imposed by covalent structure, intramolecular hydrogen bonds are expected to respond to heating less then the intermolecular hydrogen bonds.

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]