Peptide inhibitor based QCM biosensor for rapidly detecting protein kinase activity

This study has demonstrated for the first time the use of peptide inhibitor-protein kinase recognition in QCM technology for detecting protein kinase A (PKA). Because of its high affinity with the catalytic subunit of PKA, protein kinase inhibitor (PKI) peptide presented a novel and potent recognition element to detect active PKA. This PKI-based method is rapid (less than 10 min), facile, and reagentless due to its one-step detection without phosphorylation process, which exhibits unique advantages over conventional kinase assays that are time-consuming (normally more than 1 h), multi-steps, and requiring addition of several reagents in phosphorylation and detection process. The piezoelectric kinase sensor is capable of sensitively detecting protein kinase A with a detection limit of 0.061 mU μL^-1 and monitoring the binding of PKA and PKI in real-time.