Pulse Sequences for Measurement of One-Bond ¹⁵N–¹H Coupling Constants in the Protein Backbone

Author： Lerche M.H. Meissner A. Poulsen F.M. Sørensen O.W.

ISSN： 1090-7807

Source： Journal of Magnetic Resonance, Vol.140, Iss.1, 1999-09, pp. : 259-263

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Abstract

A set of three improved two-dimensional (2D) NMR methods for measuring one-bond ¹⁵N–¹H coupling constants in the protein backbone is presented. They are tailored to suit the size of the TROSY effect, i.e., the degree of interference between dipolar and chemical shift anisotropy relaxation mechanisms. The methods edit 2D spectra into two separate subspectra corresponding to the two possible spin states of the coupling partner. Cross talk between the two subspectra is a second order effect in the difference between the actual coupling constants and the one used in setting the pertinent delays of the pulse sequences. This relatively high degree of editing accuracy makes the methods useful for applications to molecules subjected to weak alignment where the one-bond coupling constants are linear combinations of a scalar J and a residual dipolar contribution containing important structural information. A demonstration of the new methods is shown for the ¹⁵N-labeled protein chymotrypsin inhibitor 2 in a lipid bicelle mixture.