Tandem mass spectrometry parent experiment

Figure 9.15 Typical mass spectrometry based experiment for protein identification/characterization. (1) Proteins are fractionated by chromatography, separated by sodium dodeyl sulphate (SDS) polyacrylamide gel electrophoresis (PAGE), then excised from gel (2) the protein of interest is digested into peptide fragments, that are then (3) identified by ESI MS/MS (4) the first dimension involves molecularion analysis for peptide mass finger-printing (ql, MS only). (5) Tandem MS/MS is used when protein identification is not unambiguous, in which case parent molecular ions are activated by CID (q2) and daughter (product) ions are characterized (ToF) according to the technique of product ion scanning (illustration from Aebersold and Mann, 2003, Fig. 1).

LC-MS and, in particular, tandem mass spectrometry (LC-MS/MS) techniques, offer a number of experiments for the determination of conjugated materials such as glucuronides from biological fluids.In LC-MS instruments, the typical analyzer used (e.g., quadrupole) analyzes ions that are sampled to the MS vacuum and generates molecular weight information that is, in most cases, limited to the parent ion. In dmg metabolism research, where often... 

The third method which provides evidence for a knotted structure is mass spectrometry.42 With electrospray ionization (ESI) it is possible to ionize the knot and other similar molecules by protonation and to transfer them into the highly diluted gas phase of a mass spectrometer. In a so-called tandem-MS experiment, the parent ion, i.e. the protonated knot, is isolated and subjected to collisions with a stationary gas inside the... 

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