Mass Spectrometry Approaches

The major advantage of the tandem mass spectrometry approach compared to MALDI peptide fingerprinting, is that the sequence information obtained from the peptides is more specific for the identification of a protein than simply determining the mass of the peptides. This permits a search of expressed sequence tag nucleotide databases to discover new human genes based upon identification of the protein. This is a useful approach because, by definition, the genes identified actually express a protein. 

Variations on the spectral peaks from different species of the same genus were also observed. Three species of Pseudomonas produced the spectra shown in Figure 14.2. These spectra are clearly unique and were used to correctly identify unknown samples. Because of peak ratio reproducibility issues in bacterial protein profiles obtained by MALDI MS,11 a fingerprint approach that had been used for other mass spectrometry approaches has not been used. The profile reproducibility problem was first recognized by Reilly et al.12,13 and later researched by others in the field.14,15 As a later alternative, a direct comparison of the mass-to-charge ratio (m/z) of the unknown mass spectral peaks with a database of known protein masses has been used to identify unknown samples.14... 

Valentine, S.J., Kulchania, M., Srebalus Barnes, C.A., Clemmer, D.E. (2001). Multidimensional separations of complex peptide mixtures a combined high-performance hquid chromatography/ion mobility/time-of-flight mass spectrometry approach. Int. J. Mass Spectrom. 212, 97-109. 

Fulcrand H, Mane C, Preys S, Mazerolles G, Bouchut C, Mazauric JP, Souquet JM, Meudec E, Li Y, Cole RB and Cheynier V. 2008. Direct mass spectrometry approaches to characterize polyphenol composition of complex samples. Phytochemistry. 69(18) 3131—3138. 

Bulet, P., and Uttenweiler-Joseph, S. (2000) A MALDI-TOF mass spectrometry approach to investigate the defense reactions in Drosophila melanogaster, an insect model for the study of innate immunity, in RM Kamp, D Kyriakidis, Th Choli-Papadopoulos, ed. Springer Proteome and Protein Analysis (Kamp, R.M., Kyriakidis, D., and Choli-Papadopoulos, T., eds.), Springer-Verlag, Berlin, pp. 157-174. 

Perhaps some idea of the power of the gas chromatography-mass spectrometry approach to the analysis of organic micropollutants can be gauged by the work of Coleman et al. [134] on mutagenic extracts of potable water. Samples of the water (1818L) were concentrated to a small volume using reverse osmosis and lyophilisation. The concentrates were then fractionated by sequential extraction with petroleum ether, diethyl... 

Casabuono, A.C., D Antuono, A.L., Sato, Y., Nonami, H., Uglade, R., Lepek, V.C., Erra-Balsells, R., Couto, A.S. A matrix-assisted laser desorption/ionization mass spectrometry approach to the lipid A from Mesorhizobium loti. Rapid Comm Mass Spectrom 20 (2006) 2175-2182. 

A gas chromatography/mass spectrometry approach to examine stereoselective ineraction of human serum proteins with soman. J. Anal. Toxicol. 32 86-91. 

Figure 2 The two most frequently used approaches for metabolomics are NMR spectroscopy and mass spectrometry. To maximize the coverage of the metabolome, these techniques can be combined. This figure shows the analysis of the aqueous fraction of a section of heart tissue that uses NMR spectroscopy, gas chromatography mass spectrometry and liquid chromatography mass spectrometry. Although mass spectrometry approaches are inherently more sensitive than NMR spectroscopy, metabolite identification becomes more difficult.

A general outline of the bottom-up mass spectrometry approach for proteome analysis is presented in Figure 3. In general, the mass spectrometry is performed at the peptide level after digesting the protein to obtain the molecular mass and amino acid sequence-specific ions, which are correlated with similar information in the protein or nucleotide database.7 16 Based upon these measurements, the following approaches have evolved. 

Chen, R., Tseng, A. M., Uhing, M., and Li, L. Application of an integrated matrix-assisted laser desorption/ionization time-of-flight, electrospray ionization mass spectrometry and tandem mass spectrometry approach to characterizing complex polyol mixtures.. Am. Soc. Mass Spectrom., 12, 55, 2001. 

Mandolmi, L., Montaudo, G., Scamporrino, E., Roelens, S., and Vitalini, D., Or-ganotm-Mediated Synthesis of Macrocyclic Tetraesters. A Combined H-NMR Spectroscopy, Gel Permeation Chromatography, and Fast Atom Bombardment Mass Spectrometry Approach to Complete Product Analysis, Macromolecules, 22, 3275, 1989. 

Danan, L. M., Yu, Z., Ludden, P.J.,Jia, W., Moore, K. L., Leary, J. A. (2010). Catalytic mechanism of Golgi-resident human tyrosylprotein suIfotransferase-2 A mass spectrometry approach. Jouma/ of the American Society for Mass Spectrometry, 21(9), 1633—1642. 

Mass Spectrometry Analysis The following mass spectrometry approaches are commonly used in proteomics for protein identification (see Figure 8.7) ... 

Yates JR, Ruse Cl, Nakorchevsky A. Proteomics by mass spectrometry approaches, advances, and applications. Annu Rev Biomed Eng 2009 11 49—79. 

Pi, N., Yu, Y., Mougous, J.D., Leary, J.A. (2004) Observation of a Hybrid Random Ping-Pong Mechanism of Catalysis for NodST A Mass Spectrometry Approach. Protein Sci. 13 903-912. 

LASER-BASED THIN-LAYER CHROMATOGRAPHY-MASS SPECTROMETRY APPROACHES PERFORMED UNDER AMBIENT CONDITIONS... 

A number of other investigators have used the TLC/extraction/mass spectrometry approach. In many of these situations, GC/MS was unavailable or unsuited for the separation of the particular class... 

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