title: A digital microfluidic system for the investigation of pre-steady-state enzyme kinetics using rapid quenching with MALDI-TOF mass spectrometry.
abstract: A digital microfluidic system based on electrowetting has been developed to facilitate the investigation of pre-steady-state reaction kinetics using rapid quenching and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The device consists of individually addressable electrodes arranged to allow the combination of liquid droplets at well-defined time intervals and an integrated, electrohydrodynamically driven mixer. The device combines two droplets to initiate a reaction, then, with precise timing, combines a third droplet to quench the reaction, and finally combines a fourth droplet to form a matrix. Improvements to throughput when compared to traditional laboratory-scale methods, and previous MALDI-TOF MS digital microfluidic systems, were made. The device was tested against a model protein tyrosine phosphatase system, and results agreed well with published data. The system therefore allows for the analysis of reaction kinetics that were previously too rapid to analyze using MALDI-TOF MS.
authors.affiliation: MESA+ Institute for Nanotechnology, Mesoscale Chemical Systems, Meander 151, University of Twente, Postbus 217, 7500 AE Enschede, The Netherlands. k.p.nichols@utwente.nl
authors.forename: Kevin Paul
authors.initials: KP
authors.lastname: Nichols
authors.forename: Han J G E
authors.initials: HJ
authors.lastname: Gardeniers
mesh_terms: D002138:Calibration; D004583:Electrons; D007700:Kinetics; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods*; D011189:Potassium Chloride; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D011189:Potassium Chloride; D017027:Protein Tyrosine Phosphatases