**1. Introduction**

The changes of the research strategy in the biochemical field driven by technological advancements occurred in these years allowed proteomics to progress and become one of the most captivating

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

branches of biochemistry. It is no exaggeration to say that, thanks to the significant step forward in the sensitivity and specificity of analytical methods, (almost) all proteins expressed by an organism can be detected/quantified even in extremely complex biological matrices. The monitoring of protein expression patterns in clinical specimens may indeed offer great opportunities to establish sets of biomarkers potentially associated with a specific disease status [1–8]. Despite these advantages, the question arises whether the application of these sophisticated proteomic procedures have profoundly affected the study of human diseases. If the number of publications in this field counts for something, the answer is undoubtedly positive. Through its ability to provide insights into both specific and system-level changes in cell, tissue and human physiology, proteomics has driven the progress observed in the last years in the elucidation of a variety of multifactorial pathological conditions, including less commonly diagnosed disorders [9–13]. In clinical proteomics several tissues and/or biological fluids are routinely analyzed for expressed proteins. Obviously, to make these analyses quantitative and reproducible, reliable profiling procedures should be established. Such procedures must rely on efficient and robust separation systems whose pivotal role is to make the complexity of mixtures simpler. Electrophoretic separations, both in-gel (1-DE and 2-DE) and in-solution (capillary electrophoresis (CE) and liquid chromatography (LC) approaches, both coupled to mass spectrometry (MS)), are currently the most attractive strategies toward the separation of hundreds/thousands of proteins. While acknowledging a remarkable success of electrophoretic approaches over the years, their intrinsic limitations cannot be hushed up. For example, the poor (if any) resolution of hydrophobic membrane proteins or of proteins that are too basic/acidic or too large/small is a well-known limit of 2-DE. The high protein amount required, the long time needed to run the samples, and the difficulty in automating the whole system are additional potential drawbacks of these techniques. The advent of LC-based procedures, characterized by unquestionable advantages, seemed to mark the fate of electrokinetic methods in the proteomic area. Being a bit of years elapsed, it can be argued that, despite the strong competition with LC, gel-based techniques do not appear to have lost this "struggle" yet [14–17]. Electrokinetic approaches, in fact, not only maintain their position but also still possess numerous characteristics currently unmatched by other proteomic methodologies. 2-DE approaches in fact remain the conventional procedure applied to the differential (control *vs.* diseased case) analysis of biological samples [18–24].

lavage fluid, exhaled breath condensate, sputum and urine of individuals with asthma, interstitial lung disease (ILD), cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and other "minor" pathologies. Since different fluids may serve as a rich source of information for the same disorder, specific subsections inside each paragraph have been dedicated to the

The Role of One- and Two-Dimensional Electrophoretic Techniques in Proteomics of the Lung

http://dx.doi.org/10.5772/intechopen.75042

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Given the hugeness of the subject, proteomics of lung cancer has thoroughly been investigated and greatly acknowledged elsewhere. In keeping with this large deal of literature, this topic would require a chapter dedicated, and it was intentionally left out of this chapter.

Since electrokinetic approaches play a pivotal role throughout the whole chapter, a few details about the principles of techniques cited in the following paragraphs will be given here. The term "electrokinetics" refers to the motion of charged particles by an applied electrical field. The standard laboratory technique by which charged molecules migrate through a porous matrix which

**Figure 1.** Representative examples of 1-DE, 2-DE, 2D-DIGE, and CE: panels A, B, C, and D, respectively (unpublished

presentation of the proteomic results relative to a peculiar fluid.

**3. Principles of electrokinetic procedures**

results from our laboratory).
