Electrospray ionization generated, multiply charged

The quantitation of small-sized therapeutic proteins or peptides in plasma can be conducted with EC—MS/MS detection of the intact proteins. Electrospray ionization (ESI) is the most widely used ionization technique for quantitative EC—MS/MS analysis of proteins or peptides. There are some occasions where atmospheric pressure chemical ionization (APCI) was used to circumvent matrix effects (Volosov et al., 2001). ESI typically generates multiply-charged protein or peptide ions, depending upon the number of basic charges in the polypeptide backbone. For small proteins, high abundance peaks of multiply... 

Shiea, J., Chang, D.-Y., Lin, C.-H., Jiang, S.-J. (2001) Generating Multiply Charged Protein Ions by Ultrasonic Nebulization/Multiple Channel-Electrospray Ionization Mass Spectrometry. Anal. Chem. 73 4983-4987. 

Lee,C.C.,Chang,D.Y.,Jeng,I,Shiea, . (2002) Generating multiply charged protein ions via two-step electrospray ionization mass spectrometry. Journal of Mass Spectrometry, 37,115-117. 

J. S. Sampson, A. M. Hawkridge, and D. C. Muddiman. Generation and Detection of Multiply-Charged Peptides and Proteins by Matrix-Assisted Laser Desorption Electrospray Ionization (MALDESI) Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. J. Am. Soc. Mass Spectrom., 17(2006) 1712-1716. 

Figure 5 Examples of Data Generated on an Electrospray Ionization Mass Spectrometer, (a) Proteins Typically Produce Positive, Multiply Charged Ions and (b) Oligonucleotides Generate Negative, Multiply Charged Ions. Inset are the Computer-Generated Molecular Weight Spectra...

Figure 1 First spectra demonstrating muitipiy charged proteins generated by electrospray ionization mass spectrometry. (Reprinted with permission from Mann M, Meng CK, and Fenn JB (1989) interpreting mass spectra of multiply charged ions. >Ana(yt ca/Chem/sf/y 61 1702 American Chemicai Society.)...

Progress is also made in software for mass spectral interpretation, especially for the so-called deconvolution of (mixed) ion envelopes of multiply charged protein ions generated by electrospray ionization, and for the peptide sequencing by MS-MS techniques. In that respect, the development of tools to search extensive protein and DNA databases using peptide maps, peptide molecular masses, LC retention time data, and sequence tags is an enormous... 

Kononikhin, A. S. Nikolaev, E. N. Frankevich, V. Zenobi, R. Multiply charged ions in matrix assisted laser desorption/ionization generated from electrosprayed sample layers. Eur. J. Mass Spectrom. 2005, 11, 257-259. 

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