Protein Dynamics Measurements by TROSY-Based NMR Experiments

The described TROSY-based experiments for investigating backbone dynamics of proteins make it possible to elucidate internal motions in large proteins via measurements of T ₁ , T ₂ , and NOE of backbone ¹⁵ N nuclei. In our proposed sequences, the INEPT sequence is eliminated and the PEP sequence is replaced by the ST2-PT sequence from the HSQC-based experiments. This has the benefit of shortening the pulse sequences by 5.4 ms (=1/2J) and results in an increase in the intrinsic sensitivity of the proposed TROSY-based experiments. The TROSY-based experiments are on average of 13% more sensitive than the corresponding HSQC-based experiments on a uniformly ¹⁵ N-labeled Xenopus laevis calcium-bound calmodulin sample on a 750-MHz spectrometer at 5°C. The amide proton linewidths of the TROSY-based experiments are 2-13 Hz narrower than those of the HSQC experiments. More sensitivity gain and higher resolution are expected if the protein sample is deuterated.