Phospho-L-tyrosine

In enzymatic reactions, the transfer proceeds via phosphorylation of the OH function of the serine residue however, threonine and tyrosine can be also involved. Hence, much attention has been paid to the fundamental study of the compounds shown in Scheme 2.36 The attractiveness of these models is due to the fact that X-ray structures both for enantiomeric and racemic forms are known (with exception of O-phospho-L-tyrosine). With the local geometry of phosphate groups and hydrogen bonding pattern taken from X-ray studies, it is possible to test the correctness of NMR analysis, the accuracy of measured structural constraints and the applicability of theoretical methods (ab initio, density functional... 

Micera, G., Strinna Erre, L., and DaUocchio, R., Metal complex formation on the srrrface of amorphous aluminirrm hydroxide. Part III. Copper(n) complexes of O-phospho-L-serine and O-phospho-L-tyrosine, Colloids Surf., 32, 249, 1988. 

The structure and function of phosphoproteins has provoked much interest in the past year. The application of n.m.r. to the study of protein structure and function has been reviewed while the stereochemistry of enzymic phosphoryl transfer and the enzymology of kinases have been described in recent volumes of Methods in Enzymology. The identification of the sites of phosphorylation on phosphoproteins is an important prerequisite in attempting the elucidation of the functions of these compounds and methods have been described for the detection of 0-phosphoserine and 0-phosphotyrosine residues in proteins. The enzymic phosphorylation and dephosphorylation of tyrosine residues in proteins has been investigated, and a simple synthesis of O-phospho-L-tyrosine from the amino acid and a phosphoric oxide/orthophosphoric acid mixture has been described. ... 

PhP = phenyl phosphate, p-Tyr = 0-phospho-L-tyrosine, MeP = methyl phosphate, diMeP = dimethyl phosphate, ATP = adenosine 5 -triphosphate, ADP = adenosine 5 -di-phosphate, AMP = adenosine 5 -monophosphate, cAMP = adenosine 3, 5 -cyclic monophosphate. 

Solid state 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 CP buildup rates and longitudinal relaxation times of P and H were determined and compared with the values measured for a triphosphate bound to a crystalline protein. It was shown that the phosphorylated amino acids are well-suited model compounds, e.g. for the optimisation of experiments on crystalline proteins. In addition, from 2D exchange experiments on O-phospho-L-tyrosine the existence of an exchange between the two different conformations of the molecule was deduced. 

It has been shown that phosphorylation changes the local conformation of a protein and thereby affects the activity of the complete protein. 341 Phosphorylation of serine and threonine side chains often occurs (Scheme 2). Phosphoamino acids are readily characterized using 3H and 31P NMR experiments. The H and 31P NMR parameters are distinct for phosphorylated serine, threonine, and tyrosine and have also been used to identify both cis-and trans-O-phospho-4-hydroxy-L-proline. 35 Phosphorylation of Cys is rare, but it can be identified by NMR even in large proteins. 36 ... 

Witucki, L. A., Huang, X., Shah, K., Liu, L., Kyin, S., Eck, M. J., and Shokat, K. M. 2002. Mutant tyrosine kinases with unnatural nucleotide specificity retain the structure and phospho-acceptor specificity of the wild-type enzyme. 

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