A new approach for obtaining sequential assignment of large proteins

A novel NMR experiment for obtaining sequential assignment of large protein s and protein complexes is described. The proposed method takes full advant age of transverse relaxation optimized spectroscopy (TROSY) and utilizes sp in-state-selection to distinguish between intraresidual and sequential conn ectivities in the HNCA-TROSY-type correlation experiment. Thus, the intra- and interresidual cross peaks can be identified without relaying magnetizat ion via carbonyl carbon, which relaxes very rapidly at the high magnetic fi elds where TROSY is most efficient. In addition, the presented method enabl es measurement of several scalar and residual dipolar couplings, which can potentially be used for structure determination of large proteins.