changes in protein profiles in bortezomib applied multiple myeloma ...
changes in protein profiles in bortezomib applied multiple myeloma ...
changes in protein profiles in bortezomib applied multiple myeloma ...
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2.1.4.5.3. Detectors<br />
Dedector is the f<strong>in</strong>al component of a mass spectrometer. After the ions pass<br />
through the analyzer, they arrive and hit the surface of the dedector and then it<br />
determ<strong>in</strong>es ion abundance for each correspond<strong>in</strong>g ion resolved by the mass analyzer<br />
depend<strong>in</strong>g on their m/z value and generates a mass spectrum (Micallef et al., 2010).<br />
Detectors can be categorized <strong>in</strong> two class. First category of detectors are<br />
responsible for measur<strong>in</strong>g of the charges that reach the detector directly. Second<br />
category of detectors play a central role to <strong>in</strong>crease the <strong>in</strong>tensity of signals. While<br />
photographic plate and the Faraday cage are comprised <strong>in</strong> the first category,<br />
photomultiplier, electron multiplier and microchannel detectors are <strong>in</strong>cluded <strong>in</strong> the<br />
second category.<br />
2.1.4.6. Tandem Mass Spectrometry (MS/MS)<br />
The basic pr<strong>in</strong>ciple of tandem mass spectrometry (MS/MS) is to isolate the<br />
precursor ion <strong>in</strong> the first spectrometer and then analyze the product ions <strong>in</strong> the second<br />
spectrometer. The process beg<strong>in</strong>s with select<strong>in</strong>g an ion. Follow<strong>in</strong>g, this ion is<br />
fragmented through collision (generally with Ar) and the fragments are analyzed by the<br />
other spectrometer.<br />
2.1.5. Advantages and Drawbacks of Prote<strong>in</strong> Profil<strong>in</strong>g<br />
Although analysis of important prote<strong>in</strong>s <strong>in</strong> biological systems is important, there<br />
are several drawbacks of prote<strong>in</strong> profil<strong>in</strong>g due to techniques like mass spectrometry <strong>in</strong><br />
comb<strong>in</strong>ation with separation tools such as 2D PAGE (Washburn et al., 2001; Wolters et<br />
al., 2001; Aebersold and Mann, 2003). First of all, these techniques are labor <strong>in</strong>tensive<br />
and time consum<strong>in</strong>g for the analysis of prote<strong>in</strong>s. Improved robotics may <strong>in</strong>crease the<br />
frequency with which these techniques are utilized, as well as their efficiency.<br />
Secondly, 2D PAGE lacks the sensitivity to detect low quantities of prote<strong>in</strong>s and<br />
therefore requires a significant quantity of biological material (Sydor and Nock, 2003;<br />
Issaq and Veenstra, 2008). Additionally, most of the time high-quantity prote<strong>in</strong>s can<br />
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