Novel sheathless CE-MS interface as an original and powerful infusion platform for nanoESI study: from intact proteins to high molecular mass noncovalent complexes
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Development of nano-electrospray (nanoESI) sources allowed to increase significantly the sensitivity which is often lacking when studying biological noncovalent assemblies. However, the flow rate used to infuse the sample into the mass spectrometer cannot be precisely controlled with nanoESI and the robustness of the system could represent an issue. In this study, we have used a sheathless capillary electrophoresis–mass spectrometry (CESI) prototype as a nanoESI infusion device. The hydrodynamic mobilization of the capillary content was characterized and the ability of the system to generate a stable electrospray under controlled flow rate conditions ranging from 4 up to 900 nL/min was demonstrated. The effect of the infusing flow rate on the detection of an intact model protein analyzed under native conditions was investigated. Results demonstrated a significant increase in sensitivity of 46-fold and a signal-to-noise ratio improvement of nearly 5-fold when using an infusing flow rate from 456.9 down to 13.7 nL/min. The CESI prototype was further used to detect successfully the β ring homodimer in its native conformation. Obtained results were compared with those achieved with conventional ESI. Intensity signals were increased by a factor of 5, while sample consumption decreased 80 times. β ring complexed with the P14 peptide was also studied. Finally, the CESI interface was used to observe the quaternary structure of native hemocyanins from Carcinus maenas crabs; this high molecular complex coexisting under various degrees of complexation and resulting in masses ranging from 445 kDa to 1.34 MDa.
KeywordsSheathless capillary electrophoresis Mass spectrometry Noncovalent complexes
Sheathless capillary electrophoresis
Rabah Gahoual would like to thank the MRT for funding his Ph.D. work. LSMIS would like to thank Beckman Coulter Inc. for lending a prototype capillary electrophoresis system and for their global support, especially Michel Anselme, Hans Dewald and Edna Betgovargez, and Bruker Daltonics Inc. for the loan of a MicroTOFQ MS. The authors would like to acknowledge Dr. Dominique Burnouf (IBMC, Strasbourg) for providing β ring samples and Dr. Frank Zal from Biological Station of Roscoff (France) for hemocyanin samples.
- 23.Gahoual R, Burr A, Busnel JM, Kuhn L, Hammann P, Beck A, François YN (2013) mAbs 5:479–490.Google Scholar