Polychromatic Selective Population Inversion for TROSY Experiments with Large Proteins

摘要

This paper presents polychromatic selective polarization inversion (PC-SPI) as an alternative to the polarization transfer methods recently developed for the application of NMR to large biological molecules.Theoretical and numerical considerations indicate that PC-SPI has the potential for more efficient polarization transfer under conditions of rapid transverse relaxation compared to J coupling- and cross-correlated relaxation-based transfers.The main advantage offered by the method presented here is the maintenance of near-optimal trajectories of inversion of the individual components of the spin magnetization while using broadband optimized pulses.A 2D experiment was implemented combining PC-SPI with TROSY-based chemical shift correlation.The experiment was applied to detect ~(15)N-1H chemical shift correlation spectra of a 200 kDa complex consisting of an 80% ~2H- and uniformly ~(15)N,~(13)C-labeled 22 kDa portion of complement receptor type 1 and unlabeled C3b of complement (180 kDa).