1. Online quench-flow electrospray ionization fourier transform ion cyclotron resonance mass spectrometry for elucidating kinetic and chemical enzymatic reaction mechanisms
- Author
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Clarke, David J., Stokes, Adam A., Langridge-Smith, Pat, and Mackay, C. Logan
- Subjects
Ion cyclotron resonance spectrometry -- Methods ,Ion cyclotron resonance spectrometry -- Technology application ,Enzymes -- Chemical properties ,Fourier transformations -- Research ,Ionization -- Research ,Chemical reaction, Rate of -- Research ,Chemical reactions -- Research ,Technology application ,Chemistry - Abstract
We have developed an automated quench-flow microreactor which interfaces directly to an electrospray ionization (ES1) mass spectrometer. We have used this device in conjunction with ESI Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) to demonstrate the potential of this approach for studying the mechanistic details of enzyme reactions. For the model system chosen to test this device, namely, the pre-steady-state hydrolysis of p-nitrophenyl acetate by the enzyme chymotrypsin, the kinetic parameters obtained are in good agreement with those in the literature. To our knowledge, this is the first reported use of online quench-flow coupled with FrICR MS. Furthermore, we have exploited the power of FTICR MS to interrogate the quenched covalently bound enzyme intermediate using top-down fagmentafion. The accurate mass capabilities of FTICR MS permitted the nature of the intermediate to be assigned with high confidence. Electron capture dissociation (ECD) fragmentation allowed us to locate the intermediate to a five amino acid section of the protein-which includes the known catalytic residue, [Ser.sub.195]. This experimental approach, which uniquely can provide both kinetic and chemical details of enzyme mechanisms, is a potentially powerful tool for studies of enzyme catalysis. 10.1021/ac9026302
- Published
- 2010