TY - JOUR
T1 - The Influence of a Scalar-Coupled Deuterium upon the Relaxation of a 15N Nucleus and Its Possible Exploitation as a Probe for Side-Chain Interactions in Proteins
AU - Boyd, Jonathan
AU - Mal, Tapas K.
AU - Soffe, Nick
AU - Campbell, Iain D.
N1 - Funding Information:
This work is a contribution from the Oxford Centre for Molecular Sciences, which is supported by the BBSRC and MRC. The 750 MHz NMR instrument was partly funded by the LINK protein engineering project with industrial partners Zeneca and Oxford Instruments. One of us, T.K.M., thanks the INLAKS foundation for financial support.
PY - 1997/1
Y1 - 1997/1
N2 - The magnitude of the quadrupole coupling constant (e2Qq1ℏ) of a deuteron is a good probe for hydrogen bonding. In protein structures, hydrogen-bonding interactions between side chains, between side chains and ligands, and between side chains and solvent are frequently found. An experiment that detects, via scalar coupling, the influence of a deuteron on the 15N nucleus of asparagine or glutamine side chains is presented. The experiment depends upon the resolution of the 1Δ15N (D) isotope shifts that allow the various isotopomers and isotopologues to be distinguished when 15N-labeled samples are dissolved in solvent mixtures of H2O/D2O. 15N lineshapes with theoretical simulations that provide estimates for the 2H quadrupole coupling constants are presented. The influence of 15N-2H dipolar-quadrupole cross correlation and the resulting small frequency shifts in the 15N multiplet are resolved in some of the spectra. The experimental data are provided using the free amino acids asparagine and glutamine for which the side chains were isotopicafly enriched in 15N and the recombinant pair of modules, flbronectin type 1 and epidermal growth factor, (F1-G) of tissue plasminogen activator, which were uniformly isotopically enriched in 15N.
AB - The magnitude of the quadrupole coupling constant (e2Qq1ℏ) of a deuteron is a good probe for hydrogen bonding. In protein structures, hydrogen-bonding interactions between side chains, between side chains and ligands, and between side chains and solvent are frequently found. An experiment that detects, via scalar coupling, the influence of a deuteron on the 15N nucleus of asparagine or glutamine side chains is presented. The experiment depends upon the resolution of the 1Δ15N (D) isotope shifts that allow the various isotopomers and isotopologues to be distinguished when 15N-labeled samples are dissolved in solvent mixtures of H2O/D2O. 15N lineshapes with theoretical simulations that provide estimates for the 2H quadrupole coupling constants are presented. The influence of 15N-2H dipolar-quadrupole cross correlation and the resulting small frequency shifts in the 15N multiplet are resolved in some of the spectra. The experimental data are provided using the free amino acids asparagine and glutamine for which the side chains were isotopicafly enriched in 15N and the recombinant pair of modules, flbronectin type 1 and epidermal growth factor, (F1-G) of tissue plasminogen activator, which were uniformly isotopically enriched in 15N.
UR - http://www.scopus.com/inward/record.url?scp=0030622236&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030622236&partnerID=8YFLogxK
U2 - 10.1006/jmre.1996.7482
DO - 10.1006/jmre.1996.7482
M3 - Article
C2 - 9424319
AN - SCOPUS:0030622236
SN - 1090-7807
VL - 124
SP - 61
EP - 71
JO - Journal of Magnetic Resonance
JF - Journal of Magnetic Resonance
IS - 1
ER -