BioNMR - Measuring 1HN temperature coefficients in invisible protein states by relaxation dispersion NMR spectroscopy

Measuring 1HN temperature coefficients in invisible protein states by relaxation dispersion NMR spectroscopy

Abstract A method based on the Carr-Purcell-Meiboom-Gill relaxation dispersion experiment is presented for measuring the temperature coefficients of amide proton chemical shifts of low populated â??invisibleâ?? protein states that exchange with a â??visibleâ?? ground state on the millisecond time-scale. The utility of the approach is demonstrated with an application to an I58D mutant of the Pfl6 Cro protein that undergoes exchange between the native, folded state and a cold denatured, unfolded conformational ensemble that is populated at a level of 6% at 2.5Â°C. A wide distribution of amide temperature coefficients is measured for the unfolded state. The distribution is centered about â??5.6 ppb/K, consistent with an absence of intra-molecular hydrogen bonds, on average. However, the large range of values (standard deviation of 2.1 ppb/K) strongly supports the notion that the unfolded state of the protein is not a true random coil polypeptide chain.

Content Type Journal Article
Pages 1-6
DOI 10.1007/s10858-011-9498-0
Authors
- Guillaume Bouvignies, Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
- Pramodh Vallurupalli, Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
- Matthew H. J. Cordes, Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ 85721-0088, USA
- D. Flemming Hansen, Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada
- Lewis E. Kay, Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada

- Journal Journal of Biomolecular NMR
- Online ISSN 1573-5001
- Print ISSN 0925-2738

Source: Journal of Biomolecular NMR