@article{a92be53d84c14262af4093ace1f542c9,
title = "Effective strategy to assign 1H-15N heteronuclear correlation NMR signals from lysine side-chain NH3 + groups of proteins at low temperature",
abstract = "Recent studies have shown that lysine side-chain NH3 + groups are excellent probes for NMR investigations of dynamics involving hydrogen bonds and ion pairs relevant to protein function. However, due to rapid hydrogen exchange, observation of 1H-15N NMR cross peaks from lysine NH3 + groups often requires use of a relatively low temperature, which renders difficulty in resonance assignment. Here we present an effective strategy to assign 1H and 15N resonances of NH3 + groups at low temperatures. This strategy involves two new 1H/13C/15N triple-resonance experiments for lysine side chains. Application to a protein-DNA complex is demonstrated.",
keywords = "H/C/N resonances, Lysine, NH groups, Proteins, Side chains",
author = "Alexandre Esadze and Levani Zandarashvili and Junji Iwahara",
note = "Funding Information: was 20.8 kHz. 15N shaped pulses are Lys 15Nζ-selective r-SNOB pulses (1.0 ms). 15N carrier position was 32 ppm. Delays: τ1 = 1.6 ms; τ2 = 1.1 ms; δ = 1.7 ms; and Tc = 20 ms. Phase cycles: /1 = [x, -x]; /2 = [2x, 2(-x)], /3 = [4x, 4y]; /4 = [4x, 4(-x)]; and receiver = [x, -x, -x, x, -y, y, y, -y]. Quadrature detections for indirect 15N dimensions was achieved using States-TPPI for /1 widths and numbers of complex points: 13.4 ppm and 400 points for 1H; and 2.2 ppm and 50 points for 15N. The mixing time of the 13C DIPSI-3 scheme (Shaka et al. 1988) was 16.9 ms. 1,024 scans were accumulated per FID. The total time to record the 2D (H2C)N(CC)H-TOCSY spectrum was 56 h. All spectra shown in this figure were recorded with a Bruker Avance III spectrometer equipped with a QCI cryogenic probe operated at the 1H frequency of 600 MHz Acknowledgments We thank Tianzhi Wang for maintenance of the spectrometers at UTMB NMR facility and Dan Nguyen for language editing. This work was supported by Grant R01GM105931 from the National Institutes of Health (to J.I.). Publisher Copyright: {\textcopyright} 2014 Springer Science+Business Media Dordrecht.",
year = "2014",
doi = "10.1007/s10858-014-9854-y",
language = "English (US)",
volume = "60",
pages = "23--27",
journal = "Journal of Biomolecular NMR",
issn = "0925-2738",
publisher = "Springer Netherlands",
number = "1",
}