Phosphorylation and dephosphorylation of proteins, which are catalyzed by protein kinases and protein phosphatases respectively, appears to regulate major cell functions1-5). Specially, cdc2 kinase and its homologues play an essential role in the regulation of the cell cycle and gene transcription6-9). Therefore the measurement of kinase activity is indispensable for study of cell function.

To assay for cdc2 kinase activity, the protein substrate, Histone H1, and radioactive ATP have been commonly used. This assay can be expensive, time consuming and utilize large amounts of radioactive ATP. Furthermore, Histone H1 is not a specific substrate for cdc2 kinase. The phosphorylation of Histone H1 being observed with several other protein kinases10). These drawbacks involve limitation of research installation and affection of cold ATP in the assay. MBL has developed the MESACUP® cdc2 Kinase Assay Kit to provide a simple, reliable and non-radioactive method for measuring cdc2 kinase activity. The kit is based on enzyme linked immunosorbent assay (ELISA) that utilizes a synthetic peptide as a substrate for the cdc2 kinases and a monoclonal antibody recognizing phosphorylated form of the peptide substrate (Fig. 1).

This method is as sensitive as the radioactive one and is less affected by concentrations of ATP present in reaction mixture.