On-chip protein sample desalting and preparation for direct coupling with electrospray ionization mass spectrometry

• Published in: Journal of Chromatography A 2003-06, Vol.1003 (1), p.11-19
• Main Authors: Lion, Niels, Gellon, Jean-Olivier, Jensen, Henrik, Girault, Hubert H.
• Format: Article
• Language: English
• Subjects: Adsorption; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Cysteine - chemistry; Cytochromes c - chemistry; Dithiothreitol; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Indicators and Reagents; Insulin - chemistry; Iodoacetamide; Lactoglobulin; Lactoglobulins - chemistry; Poly(vinylidene difluoride); Propranolol - chemistry; Protein Array Analysis; Proteins; Proteins - chemistry; Salts; Spectrometry, Mass, Electrospray Ionization - methods; Urea
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(03)00771-4

A membrane-based desalting step integrated in a MS microchip is presented: drugs, peptides and proteins are adsorbed on a hydrophobic poly(vinylidene difluoride) membrane, which allows the washing out of salts. The integration with microfluidics permits a controlled elution of analytes from the membrane and their direct mass spectrometric analysis by electrospray ionisation MS. The desalting process is demonstrated with picomole amounts of propanolol, insulin and cytochrome c. Moreover, this stop-and-go desalting process is tolerant to high concentrations of urea, and to the presence of reductants such as dithiothreitol. This particular feature allowed the chemical tagging of cysteines in β-lactoglobulin A with iodoacetamide. Finally, the integration of chemical tagging, on-chip desalting and MS microchip paves the way for the development of high-throughput analytical procedure for structural proteomics.