title: Charge as you like! Efficient manipulation of negative ion net charge in electrospray ionization of proteins and nucleic acids.
abstract: Acidic proteins and nucleic acids such as RNA are most readily ionized in electrospray ionization (ESI) operated in negative-ion mode. The multiply deprotonated protein or RNA ions can be used as precursors in top- down mass spectrometry. Because the performance of the dissociation method used critically depends on precursor ion negative net charge, it is important that the extent of charging in ESI can be manipulated efficiently. We show here that (M - nH)(n-) ion net charge of proteins and RNA can be controlled efficiently by  the addition of organic bases to the electrosprayed solution. Our study also highlights the fact that ion formation in ESI in negative mode is only poorly understood.
authors: University of Innsbruck, Innsbruck, Austria.
authors: Barbara
authors: B
authors: Ganisl
authors: Monika
authors: M
authors: Taucher
authors: Christian
authors: C
authors: Riml
authors: Kathrin
authors: K
authors: Breuker
mesh_terms: D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D009696:Nucleic Acids / Q000032:analysis* / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D011506:Proteins / Q000032:analysis* / Q000737:chemistry*; D012313:RNA / Q000032:analysis / Q000737:chemistry; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007477:Ions; D009696:Nucleic Acids; D009930:Organic Chemicals; D011506:Proteins; D012996:Solutions; D012313:RNA