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The solid state NMR spectroscopy was used for (super 31)P and (super 2)H relaxation studies of helix VI and the cytoplasmic helix of human cannabinoid receptor. This technique can be used to sense the physical state of the lipid bilayer as well as the molecular motions associated with acyl chains in the presence of macromolecules.

[sup.2.H] and [sup.15.N] solid-state NMR spectroscopic techniques are used to investigate the side chain and backbone dynamics of wild-type phospholamban (WT-PLB). The NMR data indicates the significant backbone motion for the cytoplasmic domain of WT-PLB when compared to the transmembrane section.

Four new swapped-domain constructs of the ectodomain of human immunodeficiency virus type 1 glycoprotein-41 (gp41) were prepared. The gp41 ectodomain consists of 50-residue N-heptad repeat (NHR), 36-residue disulfide-bonded loop and 39-residue C-heptad repeat (CHR). It folds into a hairpin structure that forms a trimer along the NHR axis. The swapped-domain proteins feature CHR domains of length 39, 28 or 21 residues preceding a 4-residue loop and a 49- or 50-residue NHR domain. The effect of CHR truncation was to expose increasing lengths of the NHR groove, including the conserved hydrophobic pocket, an important drug target. A novel method for preparing proteins with extended exposed hydrophobic surfaces was demonstrated. Biophysical measurements, including analytical ultracentrifugation and ligand-detected Water-Ligand Observed via Gradient Spectroscopy and ¹H-15N-HSQC NMR experiments, were used to confirm that the proteins formed stable trimers in solution with exposed binding surfaces. These proteins could play an important role as receptors in structure-based drug discovery. [ABSTRACT FROM AUTHOR]

The ability of several ab initio models to predict experimental Si-NMR chemical shift is examined. The shielding values of trimethylsilyl chloride (A), t-butyldimethylsilyl chloride (B) and allytrimethylsilane (C) are calculated by GIAO, CSGT and IGAIM methods, using HF/6-31G, B3LYP/6-31G, HF/6-311+G, B3LYP/6-311+G and MPW1PW91/6-311+G models respectively. The Si chemical shifts calculated by GIAO method using HF/6-311+G model are highly in agreement with those obtained experimentally. All of the models above reproduce the trends of chemical shifts in all cases studied, suggesting that the models are of practical value. [ABSTRACT FROM AUTHOR]