TROSY Based Triple-Resonance Experiments

The same holds true also for the slowly relaxing longitudinal coherences 

Sequential assignment based on alpha carbon shifts 

In principle, for each residue, two correlations emerge. One is the strong intraresidual 13C (i) correlation and the other is the usually weaker 

The overall performance is limited by the average 1/NC and 2./NC scalar coupling values that are 10.9 (9.6) Hz and 8.3 (6.4) Hz in the (1-sheet structures (a-helical structures), respectively.37 Consequently the delay 2Ta is routinely set to 25 ms. Assuming that the 15N spin-spin relaxation time for the TROSY component is 50 ms, the transfer efficiency for the intraresidual pathway, for the first t increment (/, =0), is 0.132, when we have optimized delays for the optimal intraresidual transfer in a-helices (Fig. 6). Throughputs for the sequential pathway then become 0.045 (0.058 (5-sheet). 

Four-dimensional extension of the HNCA-TROSY scheme 

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Exploitation of the TROSY effect is rather straightforward. In contrast to 15N-HSQC (Heteronuclear Single Quantum Coherence) or standard triple-resonance experiments based on 15N-HSQC, no radio frequency pulses or composite pulse decoupling should be applied on amide protons when HN spin is not in the transverse plane. Likewise the 15N decoupling should be... 

TROSY element based on DD/ C CSA compensation. Sensitivity improvement of triple resonance experiments for nucleotide bases... 

Yang D, Kay LE (1999) Improved HN-detected triple resonance TROSY-based experiments. J Biomol NMR 13 3-10... 

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