Abstract
We demonstrate here a method for eliminating cross-relaxation effects from exchange spectra of macromolecules that permits a more rigorous study of chemical-exchange processes. In the spin diffusion limit, the laboratory-frame cross-relaxationrate is negative and equal to half the rotating-frame cross-relaxation rate, which is positive. If, during the mixing time, the magnetization is flipped rapidly between the two frames such that the average residence time in the NOESY:ROESY framesis 2:1, then the magnetization exchange due to cross-relaxation will cancel out and be removed. Since chemical exchangetakes place steadily, irrespective of the frame of reference, it will contribute to cross-peak volumes in the usual manner. Thisapproach has been applied to the elimination of cross-relaxation effects from the 2D exchange spectrum of a small globularprotein, turkey ovomucoid third domain (6062 Da). The results demonstrate that tyrosine-31 executes ring flips on the millisecondtime scale.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2574-2577 |
| Number of pages | 4 |
| Journal | Journal of the American Chemical Society |
| Volume | 112 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jan 1990 |
ASJC Scopus subject areas
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry