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

Solid‐state 31P 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 31P and 1H were‐determined and compared with the values measured for a triphosphate (GppCH2p) 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.