Phosphorylated amino acids: model compounds for solid‐state 31 P NMR spectroscopic studies of proteins

Solid‐state 31 P NMR spectroscopy was applied to measure the isotropic chemical shifts, chemical shift anisotropies and asymmetry parameters of three phosphorylated amino acids, O ‐phospho‐ L ‐serine, O ‐phospho‐ L ‐threonine and O ‐phospho‐ L ‐tyrosine. The cross‐polarization buildup rates and longitudinal relaxation times of 31 P and 1 H were‐determined and compared with the values measured for a triphosphate (GppCH 2 p) bound to a crystalline protein (Ras). It is shown that the phosphorylated amino acids are well‐suited model compounds, e.g. for the optimization of experiments on crystalline proteins. Two‐dimensional exchange experiments on O ‐phospho‐ L ‐tyrosine indicate the existence of an exchange between the two different conformations of the molecule. Copyright © 2004 John Wiley & Sons, Ltd.