A method for selective labeling of
phosphate groups in natural and synthetic oligomers and polymers in the presence of chemically related groups such as
carboxylic acid groups. The method is specifically applicable to biological oligomers and polymers, including phosphopeptides, phosphoproteins and phospholipids. In a specific embodiment, selective labeling of
phosphate groups in proteins and peptides, for example, facilitates separation, isolation and detection of phosphoproteins and phosphopeptides in complex mixtures of proteins. Selective labeling can be employed to selectively introduce
phosphate labels at phosphate groups in an
oligomer or
polymer, e.g., in
a peptide or
protein. Detection of the presence of the
label, is used to detect the presence of the phosphate group in the
oligomer or
polymer. The method is useful for the detection of phosphoproteins or phosphopeptides. The phosphate
label can be a colorimetric
label, a radiolabel, a fluorescent or phosphorescent label, an
affinity label or a
linker group carrying a reactive group (or latent reactive group) that allows selective attachment of the
oligomer or
polymer (
protein or
peptide) to a phosphate label, to an
affinity label or to a
solid support. The method can be combined with well-known methods of
mass spectrometry to detect and identify phosphopeptides and phosphoproteins.