Nathan Janes

Carbon-13 chemical shielding tensors in l-threonine☆

Abstract The carbon-13 chemical shielding tensors of the amino acid L-threonine have been determined by solid state proton-enhanced NMR of a single crystal at 3.52 T. For the first time a carbinol shielding tensor is determined quantitatively and unambiguously: the most shielded axis lies 4° from the CO bond. A coordinate system which approximates the alpha carbon tensor orientation is proposed, and it is suggested that this “local symmetry” may be general to many amino acid alpha carbons. The carboxyl and methyl tensor orientations closely approximate previously established “local symmetry,” although the methyl (C γ ) C 3v symmetry is slightly disrupted, apparently by the neighboring (O γ ) oxygen. The influence of the carbon-nitrogen dipolar interaction on the observed spectra is discussed, and used to make unique assignments for the carboxyl, alpha, and beta carbon tensors.

Effects of D-myo-inositol on the transfer function of phosphatidyl linositol transfer protein alpha

The lipid metabolite D‐myo‐inositol‐1‐phosphate is shown to increase the phospholipid transfer activity of phosphatidylinositol transfer protein α from liposomal and liver microsomal membranes. Dose‐response curves indicated substantial enhancements of transfer in the low mM range that upon normalization were independent of membrane composition or the identity of the transferred phospholipid. The unnormalized effect is potentiated by anionic membrane surface charge and substantial membrane phosphatidylethanolamine content consistent with alterations of the proteins membrane binding affinity and alterations of surface electrostatic interactions as contributing factors.