Simple and Sensitive Method for Determination of Protein Kinase Activity Based on Surface Charge Change of Peptide-Modified Gold Nanoparticles As Substrates.

Protein tyrosine kinases play a pivotal role in intracellular signal transduction pathways and oncogenic transformation. It is necessary to develop a simple, cost-effective, and sensitive kinase assay for study of protein kinases and discovery of kinase-target drugs. In this paper, we present a simple and sensitive method for homogeneous detection of protein kinase activity and screening of inhibitor by measuring surface charge change on the peptide-modified gold nanoparticles (GNPs) as kinase substrates. In this assay, Abl (Abelson murine leukemia viral oncogene) kinase was used as a model. In the presence of Abl kinase and ATP, the surface negative charge on GNPs significantly increases due to phosphorylation of the peptide-modified GNPs. The surface charge on the peptide-modified GNPs was measured by zeta potential analyzer. Under the optimum conditions, the zeta potential on the peptide-modified GNPs was linearly dependent on Abl kinase concentration, the linear range was from 1 to 40 nM and the detection limit was 1 nM. This method was used to evaluate the inhibition efficiency of inhibitors, and the obtained IC50 values were well in agreement with the results reported in the references. Furthermore, this method was successfully applied to determine Abl kinase activity in the cell lysates. Compared to current methods, this new method shows simplicity, short analysis time, high sensitivity, and will become a promising platform for kinase-related fundamental research and inhibitor screening.