Catalytic enzyme activity on a biosensor chip: combination of surface plasmon resonance and mass spectrometry.

Surface plasmon resonance (SPR) as a label-free biosensor technique has become an important tool in drug discovery campaigns during the last couple of years. For good assay performance, it is of high interest to verify the functional activity on the immobilization of the target protein on the chip. This study illustrates the verification of the catalytic activity of the drug target protein PqsD by monitoring substrate conversion as a decrease in SPR signal and product detection by ultra high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS(2)). This assay would be applicable to control surface activity of immobilized ligands.