A colorimetric enzyme-linked on-bead assay for identification of synthetic substrates of protein tyrosine kinases.

Protein tyrosine kinases play key roles in the progression of numerous human diseases including several types of cancers. We report here a simple colorimetric assay for tyrosine kinase activity employing synthetic peptide substrates prepared on Tentagel synthesis beads. Phosphorylation of compounds on beads was detected with an antiphosphotyrosine antibody complexed with a secondary antibody-alkaline phosphatase conjugate. This assay may prove useful for the identification and characterization of synthetic substrates of this important class of enzymes.