Recognition of proximally phosphorylated tyrosine residues and continuous analysis of phosphatase activity using a stable europium complex.

The recognition of proteins and their post-translational modifications using synthetic molecules is an active area of research. A common post-translational modification is the phosphorylation of serine, threonine or tyrosine residues. The phosphorylation of proximal tyrosine residues occurs in over 1000 proteins in the human proteome, including in disease-related proteins, so the recognition of this motif is of particular interest. We have developed a luminescent europium(III) complex, [Eu.1]+ , capable of the discrimination of proximally phosphorylated tyrosine residues, from analogous mono- and non-phosphorylated tyrosine residues, more distantly-related phosphotyrosine residues and over proximally phosphorylated serine and threonine residues. [Eu.1]+ was used to continuously monitor the phosphatase catalysed dephosphorylation of a peptide containing proximally phosphorylated tyrosine residues.