Capillary isoelectric focusing mass spectrometry

Martinovic, S. Berger, S.J. Pasa-Tolic, L. Smith, R.D. Separation and Detection of Intact Noncovalent Protein Complexes from Mixtures by On-Line Capillary Isoelectric Focusing-Mass Spectrometry, Anal. Chem. 72, 5356-5360 (2000). 

S. Martinovic, S.J. Berger, L. Pasa-Tolic and R.D. Smith, Separation and detection of intact noncovalent protein complexes from mixtures by on-line capillary isoelectric focusing-mass spectrometry. Analytical Chemistry, 72, 5356-5360 (2000). 

N.J. Clarke and S. Naylor, Capillary isoelectric focusing-mass spectrometry analysis of protein mixtures from human body fluids, Biomedical Chromatography, 16, 287-297 (2002). 

Kuroda Y, YukinagaH, Kitano M, Noguchi T, NematiM, ShibukawaA, NakagawaT, Matsuzaki K. Online capillary isoelectric focusing-mass spectrometry for quantitative analysis of peptides and proteins. J Pharm Biomed Anal 2005 37 423-8. 

Martinovic S, Pasa-Tolic L, Smith RD. Capillary isoelectric focusing—mass spectrometry of proteins and protein complexes. Methods Mol Biol 2004 276 291-304. 

Storms HF, van der HR, Tjaden UR, van der GJ. Capillary isoelectric focusing-mass spectrometry for shotgun approach in proteomics. Electrophoresis 2004 25 3461-7. 

In E. Coli bacterial lysates, the proteome (i.e., the full array of proteins produced) was analyzed by isoelectric focusing and mass spectrometry.97 A comparison of capillary electrophoretic separation and slab gel separation of a recombinant monoclonal antibody demonstrated that the precision, robustness, speed, and ease-of-use of CE were superior.98 Seventy-five proteins from the yeast ribosome were analyzed and identified by capillary electrophoresis coupled with MS/MS tandem mass spectrometry.99 Heavy-chain C-terminal variants of the anti-tumor necrosis factor antibody DE7 have been separated on capillary isoelectric focusing.100 Isoforms differing by about 0.1 pi units represented antibodies with 0,1 or 2 C-terminal lysines. 

Jensen, P. K., Pasa-Tolic, L., Anderson, G. A., Homer, J. A., Lipton, M. S., Bmce, J. E., and Smith, R. D. (1999). Probing proteomes using capillary isoelectric focusing-electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Anal. Chem. 71, 2076-2084. 

Tang, Q., Harrata, A. K., Lee, C. S. (1997). Two-dimensional analysis of recombinant E. coli proteins using capillary isoelectric focusing electrospray ionization mass spectrometry. Anal. Chem. 69(16), 3177-3182. 

Zhou, F., Johnston, M. V. (2005). Protein profiling by capillary isoelectric focusing, reversed phase liquid chromatography, and mass spectrometry. Electrophoresis 26(7-8), 1383-1388. 

B. Michalke, P. Schramel, Application of capillary zone electrophoresisDinductively coupled plasma mass spectrometry and capillary isoelectric focusing-inductively coupled plasma mass spectrometry for selenium speciation, J. Chromatogr. A, 807 (1998), 71D80. 

The on-line interfacing of capillary isoelectric focusing with Fourier-transform ion cyclotron resonance-mass spectrometry (FTICR-MS) was shown to be effective for separating minor components of protein mixtures for on-line mass spectral analysis [62-64],... 

To remove carrier ampholytes when electrospray ionisation mass spectrometry is used on-line with capillary isoelectric focusing, a specially designed free-flow electrophoresis device can be coupled to the CIEF system [67],... 

Capillary isoelectric focusing can be applied as a micropreparative tool for protein analysis by matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) [69,70]. The exact timing of the collector steps in the interface is based on determining the velocity of each individual zone measured between two detection points close to the end of the capillary. During the collection a sheath flow fraction collector is used to maintain the permanent electric current. 

Capillary isoelectric focusing (CIEF) is a high-resolution technique for protein and peptide separation performed at academic sites and in the biotechnology and pharmaceutical industries for the analysis and characterization of, for example, recombinant antibodies and other recombinant proteins, isoforms of glycoproteins, point mutations in hemoglobin, and peptide mapping. Also, hyphenation to mass spectrometry and chip-based CIEF (microfabrication) have shown promise. CIEF kits and specific recipes/application notes are available from vendors of capillary electrophoresis (CE) equipment, as are a vast amount of publications and handbooks of CE published over recent years. 

Capillary isoelectric focusing coupled to mass spectrometry has gained popularity in recent years (by analogy to two-dimensional gel electrophoresis). Additional information obtained from mass spectrometry includes not only precise molecular-weight determination but also the possiblity for peptide sequencing. Analysis of hemoglobin variants, recombinant proteins, and monoclonal antibodies have been demonstrated [1,7,8]. 

Jensen, P.K. Pasa-Tolic, L. Anderson, G.A. Horner, J.A. Lipton, M.S. Bruce, J.E. Smith, R.D. Probing Proteomes Using Capillary Isoelectric Focusing-Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, AnaZ. Chem. 71, 2076-2084 (1999). 

Chartogne, A. Tjaden, U.R. Van der Greef, J. A Lrcc-llow Electrophoresis Chip Device for Interfacing Capillary Isoelectric Focusing On-line with Electrospray Mass Spectrometry, Rapid Commun. Mass Spectrom. 14, 1269-1274 (2000). 

Hypersensitive Measurement of Proteins by Capillary Isoelectric Focusing and Liquid Chromatography-Mass Spectrometry... 

Q. Tang, A.K. Harrata and C.S. Lee, Capillary isoelectric-focusing electrospray mass-spectrometry for protein analysis. Analytical Chemistry, 67, 3515-3519 (1995). 

L.Y Yang, C.S. Lee, S.A. Hofstadler, L. Pasa-Tolic and R.D. Smith, Capillary isoelectric focusing-electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry for protein characterization. Analytical Chemistry, 70, 3235-3241 (1998). 

T.S. Liu, X. Xiao, R. Zeng and Q. Xia, Protein isoforms observed by ultrahigh resolution capillary isoelectric focusing-electrospray ionization mass spectrometry, Shengwu Huaxue Yu Shengwu Wuli Xuebao, 34, 423 432 (2002). 

Zhoua, G-H. et al. Characterization of recombinant human granulocyte colony stimulating factor (rHuG-CSF) by capillary zone electrophoresis, capillary isoelectric focusing electrophoresis and electrospray ionization mass spectrometry. J. Pharm. Biomed. Anal., 35, 425, 2004002E. 

Wei, J., L. Yang, A. K. Harrata, and C. S. Lee, High resolution analysis of protein phosphorylation using capillary isoelectric focusing—electrospray ionization—mass spectrometry. Electrophoresis, 19, 2356-2360, 1998. 

CE provides a complementary approach to HPLC separation. It is performed in several different formats, including capillary zone electrophoresis, miceller electrokinetic chromatography, capillary gel electrophoresis, capillary isoelectric focusing, isotachophoresis, and capillary electrochromatography. Of these formats, capillary zone electrophoresis is the most popular separation technique. The most successful coupling of CE with mass spectrometry is achieved via an ESI interface. The three most practical designs are sheathless interface, sheath-flow interface, and liquid-junction interface. 

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