Mass spectrometry structural overview

Levsen K, Schiebel HM, Behnke B, Dotzer R, Dreher W, Elend M, Thiele H. Structure elucidation of phase II metabolites by tandem mass spectrometry an overview. J Chromatogr A 2005 1067 55-72. 

R 420 K. Levsen, H.-M. Scheibel, B. Behnke, R. Doetzer, W. Dreher, M. Elend and H. Thiele, Structure Elucidation of Phase II Metabolites by Tandem Mass Spectrometry An Overview , J.Chromatogr., A, 2005,1067,55... 

In line with the policy of Advances to provide periodic coverage of major developments in physical methodology for the study of carbohydrates, A. Dell (London) here surveys the use of fast-atom-bombardment mass spectrometry in application to carbohydrates. This technique has achieved rapid prominence as the soft ionization technique of choice for structural investigation of complex carbohydrate sequences in biological samples. The author s extensive personal involvement in this field makes her chapter a critical, state-of-the-art overview for the specialist, as well as a valuable primer for the reader unfamiliar with this technique. 

Mass spectrometry is the method of choice for the structural characterization of secondary modifications. An overview over the diversity of this field is beyond the scope of this chapter and only the principal methods used are described. 

In this chapter, we give an overview on how the API techniques work and which factors have an important influence on the performance. Examples are presented mostly from published work to demonstrate how LC-MS, LC-MS-MS, collision-induced dissociations (CIDs), accurate mass measurements and hydro-gen/deuterium exchange have been systematically and successfully applied in the structural elucidation of impurities, degradation products and metabolites. In addition, these also illustrate how mass spectrometry has offered a third dimension to chromatographic method development and validation. 

Overview of Semi-Empirical and Ab Initio Molecular Orbital Methods. 2.2 Applications of Molecular Mechanics. 3 Experimental Structural Methods. 3.1 X-Ray Diffraction. 3.2 NMR Spectroscopy and. 3.3 Mass Spectrometry. 3.4 UV/Fluorescence. 3.5 IR Spectroscopy. 3.6 Redox Potentials. 4 Thermodynamic Aspects. 4.1 Melting Points. 5 Reactivity of Fully Conjugated Rings 6 Reactivity of Nonconjugated Rings... 

In addition, stilbenes are fluorescent compounds which are easily detected by flu-orometry. For resveratrol, fluorescence detection is highly selective and even twice as sensitive as UV detection (Stecher et al. 2001). Due to this potential, methods by using HPLC coupled with absorbance and fluorescence detection were developed (Jeandet et al. 1997 Vitrac et al. 2002). Otherwise identification of stilbenes in wine by HPLC-DAD can be limited by coelution of two or more compounds. Therefore application of modern mass-spectrometry techniques is important to confirm the structure of stilbenes and to detect novel compounds in wine (Monagas et al. 2005b Buiarelli et al. 2007 Careri et al. 2004 Jean-Denis et al. 2006 Kammerer et al. 2004 Mark et al. 2005 Piissa et al. 2006 Stecher et al. 2001). Table 9C. 1 shows an overview on stilbenoid molecular ions and fragments identified in wine and grapevine by mass spectrometry. 

We present an overview of the structures for 3-alkylpyridine and 3-alkylpyridinium compounds that have been isolated, taking into account the structural characterization of alkylpyridinium compounds and discussing the central role played by mass spectrometry. Concerning their synthesis, both the natural pathways and organic synthesis of pyridinium alkaloids are reviewed. Synthetic aspects of 3-alkylpyridines have been taken into account only where relevant for structural modifications or for the assignment of absolute configurations. Finally, biological activities of both 3-alkylpyridine and 3-alkylpyridinium compounds and the potential use of the latter are discussed. 

Chapter 5 provides an overview of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and its applications in the structural characterization of peptides and proteins. The principles of FT-ICR, that is, ion motion, ion excitation/ detection, and instrumental considerations, are discussed and an explanation of the features of FT-ICR that make it so suitable for peptide/protein analysis is presented. New methods for the fragmentation of peptide and protein ions in FT-ICR mass spectrometry, such as sustained off-resonance irradiation collision-induced dissociation (SORI-CID), infrared multiphoton dissociation (IRMPD), blackbody infrared radiative dissociation (BIRD), surface-induced dissociation (SID), and electron capture dissociation (BCD), are described in detail. Innovative hybrid FT-ICR instruments, which have recently become available, are reviewed. In conclusion, the chapter discusses the applications of FT-ICR in bottom-up and top-down proteomics. 

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