In this review, the main classical gel-based methods (2-DE, DIGE) are discussed, as well as the advances of gel-free quantitative proteomic techniques, from metabolic and chemical labeling (SILAC, iTRAQ, ICAT, 16O/18O, QconCAT) to nonlabeling (MS spectra counting and peak integration) strategies.
In our EL spectra counting, the peak intensity of LEDs with Au nanoparticles from the 2- and 5-nm Au-CNT systems were 290.8 and 264.6, respectively, compared with 187.2 for conventional LEDs.
Assignment of the major protein(s) from each gel feature was achieved using quantitative proteomics from spectra counting [38].
The mass spectra (counts versus mass/charge values for m/z 100 to 700) were exported to Excel 2007 (Microsoft Inc., Belleview, WA, USA) for data pre-processing and then to JMP 9.0 (division of SAS Institute Inc ,Cary, North Carolina, USA) to perform artificial neural network (ANN) analysis (Onofrejová et al. [2007]; Korel and Balaban [2008]).
In addition, the PfPMT, a key enzyme in the SDPM pathway as well as the S-adenosylmethionine synthetase (PFI1090w, which provides the PfPMT essential cofactor S-adenosylmethionine), showed an increase in treated versus untreated spectral counts (17 versus 5 spectra counts for PfPMT and 7 versus 2 spectral counts for PFI1090w in T4 treated and untreated parasites, respectively).
Next, Mass Frontier 4 was used to predict the tandem mass spectra of the candidates, which were matched to the measured spectrum, counting the number of common peaks.
Other methods, based on spectrum counting [23], are limited in their ability to detect low abundance proteins.
Yet a "startling fact" emerged: four of ten of those who qualified as conservatives on the ideological spectrum counted as liberal on the operational spectrum.
Differential expression of plasma proteins was estimated by comparing spectrum counts [12], [13], and significant differences determined by Mann-Whitney U test using Statview software (SAS Inc, Cary, NC, USA).
We used normalized spectrum counts to perform relative quantification and identify age- and SPARC-related changes (Table 1).
Spectral counting entails averaging the spectrum counts across the different protein samples tested, followed by calculating the quantitative value for each identified protein.
