Activity measurement of protein kinase and protein phosphatase by microchip phosphate-affinity electrophoresis

AbstractWe previously proposed microchip-based phosphate-affinity electrophoresis (μPAE) and demonstrated its application to activity measurement of a tyrosine kinase, c-Src. In this study, we extended the μPAE application to a serine/threonine kinase, protein kinase A (PKA), and to a tyrosine phosphatase, leukocyte antigen-related protein tyrosine phosphatase (LAR PTPase). For standard peptide samples, we obtained linear calibration plots, and the limits of detection were 1.2% (PKA) and 1.5% (LAR PTPase) product peptides in the total peptides. The μPAE was also proven to be effective for unpurified enzyme reaction products