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Determination of the Protein Backbone Dihedral Angle ψ from a Combination of NMR-Derived Cross-Correlation Spin Relaxation Rates

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journal contribution
posted on 09.09.1998, 00:00 by Daiwen Yang, Lewis E. Kay
A sensitive triple resonance NMR experiment is presented for the measurement of the protein backbone dihedral angle ψ based on cross-correlated spin relaxation between 13Cα1Hα and 15N−1HN dipolar interactions in 15N,13C-labeled proteins. In general, as many as four ψ values can be consistent with a single cross-correlation rate. However, in many cases, the ambiguity can be significantly reduced (for example, from four to two) when a combination of cross-correlation relaxation rates are employed. This is illustrated by considering rates derived from 13Cα1Hα/15N−1HN dipolar and from 13Cα1Hα dipolar/carbonyl chemical shift anisotropy relaxation mechanisms for the proteins ubiquitin and CheY. Using a database of ψ values obtained from high-resolution X-ray structures, it is shown that for values in the range −50° ≤ ψ ≤ 40° a single ψ can be obtained to high probability.