Surface enhanced laser desorptions ionization-time of flight-mass spectrometry analysis in complex food and biological systems

SELDI-TOF-MS of saliva: Methodology and pre-treatment effects

“…Second, competitive binding of high abundance non-informative proteins (like the mucins) on the chip surface may reduce the intensity of peptides/proteins of interest, particularly the low abundance ones. This can be overcome by pre-fractionation of the saliva sample or the use of membranes with a specific cut-off, as suggested by Rawel et al [27]. However, pre-treatment using a membrane with a cutoff of 10 kDa had little or no effect on the spectra (results not shown), from 0 to 10 kDa indicating that the high-molecular weight proteins do not interfere with the profiles using IMAC-Cu chips.…”

Nature of hydroxycinnamate-protein interactions

“…Other analytical strategies include: utilizing the UVVis characteristics of the bound phenolics (Rawel et al 2002;Rohn et al 2004;Seifert et al 2004); reduction of the reactive amino acid sites involved in the covalent interactions ; amino acid analysis and comparison with the results obtained for unmodified protein (Petzke et al 2005;Rohn et al 2006), and chromatographic and electrophoretic techniques (Rawel et al 2002;Montavon et al 2003a, b). A more recent method to characterize such protein modifications involves the application of a soft ionization technique in mass spectrometry such as MALDI-or SELDI-TOF-MS Rawel et al 2005c). In context of the studies, it was possible to characterize the modification of selected proteins (myoglobin, milk whey proteins, soy proteins, lysozyme) in the presence of plant phenols (chlorogenic-, caffeic, ferulic-and gallic acid, quercetin, rutin, genistein, daidzein, formonetin, prunetin, biochanin A as well as synthetic isoflavones) in model systems (Kroll et al 2000;Kroll and Rawel 2001;Rawel et al 2001aRawel et al , 2003Rawel et al , 2004Rawel et al , 2005c.…”

“…In context of the studies, it was possible to characterize the modification of selected proteins (myoglobin, milk whey proteins, soy proteins, lysozyme) in the presence of plant phenols (chlorogenic-, caffeic, ferulic-and gallic acid, quercetin, rutin, genistein, daidzein, formonetin, prunetin, biochanin A as well as synthetic isoflavones) in model systems (Kroll et al 2000;Kroll and Rawel 2001;Rawel et al 2001aRawel et al , 2003Rawel et al , 2004Rawel et al , 2005c. Such methods may also allow the identification of reaction sites in a protein by combination of peptide mass fingerprinting using specific endoproteases with protein database searches (Rawel et al 2005c). The drawback of all these methods is that the adducts formed with the different amino acids or the protein side chains have not yet been fully characterized.…”

SALDI-MS Signal enhancement using oxidized graphitized carbon black nanoparticles

“…One approach to improve sensitivity is to concentrate the sample on a plate, as in surface-enhanced laser desorption ionization (SELDI) [13], or on a medium that can act as a SALDI matrix. Graphitized carbon black has been recently used as a bifunctional material to concentrate small molecules (as a solid-phase extraction sorbent) and to act as a SALDI medium [11].…”