Current Organic Chemistry, Volume 9, No. 9, 2005
Contents
Analytical
Methods in Organic Chemistry
Guest
Editors: Atta-ur-Rahman and Klaus-Peter Zeller
Editorial Pp.823-823
Atta-ur-Rahman and Klaus-Peter Zeller
Mass Spectrometry in Doping Control Analysis Pp.825-848
M. Thevis and W. Schanzer
Liquid Chromatographic- Mass Spectrometric Methods for
the Analysis of Persistent Pollutants: Polycyclic Aromatic Hydrocarbons,
Organochlorine Compounds and Perfluorinated Compounds Pp.849-857
H. Moriwaki
Liquid Chromatography Tandem Mass Spectrometry as a
Tool to Investigate Pesticides and Their Degradation Products Pp.859-873
Claudio Medana, Paola Calza, Claudio Baiocchi and Ezio
Pelizzetti
Functional Protein Analysis Using Mass Spectrometry Pp.875-887
Simone Konig
Overview of Common Spectroscopic Methods to Determine
the Orientation/Alignment of Membrane Probes and Drugs in Lipidic Bilayers Pp.889-898
Sílvia C. D. N. Lopes and Miguel A. R. B. Castanho
Analysis of Biological Macromolecular Assemblies Using
Static Light Scattering Methods Pp.899-908
LeAnn J. Godderz, Mandy M. Peak and Karla K. Rodgers
Biological Imaging and Spectroscopy of pH Pp.909-923
Valery V. Khramtsov
Abstracts
[Back to top] Editorial
Atta-ur-Rahman and Klaus-Peter Zeller
In this issue the reader finds four review articles illustrating the superiority of modern mass spectrometry in several fields of applications:
In their article, Thevis and Schänzer summarize the achievements made by mass spectrometric techniques to prove doping of athletes. It can be stated that mass spectrometry in combination with advanced separation methods is the only way to cope with doping, the ugly face of the contemporary sport. The two following articles by Moriwaki and Medana, Calza, Baiocchi and Pelizzetti cover the role of mass spectrometry in the analysis of persistent pollutants and pesticides. Both reviews nicely demonstrate the high impact of MS techniques in an area of enormous importance for modern societies. However, mass spectrometry is not only a method to determine the occurrence of molecules in body fluids or environmental matrices. As shown by König it has also established a firm position in functional protein analysis.
Three articles of this issue emphasize the power of spectroscopic methods in life sciences: Lopes and Castanho overview the common spectroscopic methods that enables the study of the orientation of membrane probes and drugs in lipidic bilayers. These are FTIR linear dichroism, UV-Vis linear dichroism, time-resolved fluorescence anisotropy, NMR and surface plasmon resonance. The results obtained by these methods are of importance for molecular drug design and ligand-receptor interactions. Godderz, Peak and Rodgers elegantly describe the use of multiple-angle laser light scatterings (MALLS) to obtain insights in protein-protein and protein-DNA interactions. The article of Khramtsov addresses non-invasive spectroscopic approaches for biological pH detection. It is shown that absorbtion and fluorescence probes are effective for pH studies in cellular and subcellular levels, whereas magnetic resonance spectroscopy (ESR, NMR) is advantageous for in vivo applications in animals and humans.
The editors thank all authors for their efforts in providing a broad readership with insights in advanced techniques with high problem-solving potential.
[Back to top] Mass Spectrometry in Doping Control Analysis
M. Thevis and W. Schanzer
Mass spectrometry has become the most frequently employed technique in doping control analysis to identify prohibited compounds ever since their use has been banned by international federations. In combination with gas or liquid chromatography and various ionization methods such as electron or chemical ionization, electrospray, atmospheric pressure chemical ionization, atmospheric pressure photo ionization or matrix-assisted laser desorption ionization, numerous applications have been established enabling the sensitive and selective detection of prohibited drugs in matrices such as urine, blood, and hair. The classes of investigated compounds include low molecular weight drugs such as anabolic steroids, diuretics, b2-agonists and b-receptor blocking agents, and others as well as high molecular weight therapeutics, for instance plasma volume expanders based on polysaccharide structures (e.g. hydroxyethyl starch and dextran), hemoglobin-based oxygen therapeutics (e.g. Hemopure), or synthetic insulins. Assays for their identification are commonly based on extractive purification, chemical or enzymatic treatment (i.e. derivatization or degradation) followed by chromatographic and mass spectrometric analysis employing various modern analyzers such as quadrupole, ion trap, triple-quadrupole and magnetic-sector mass spectrometers allowing the sensitive and unambiguous qualitative as well as quantitative determination of xenobiotics in elite athletes’ doping control samples. Moreover, the administration of drugs naturally occurring in human beings, for instance testosterone, is uncovered by carbon isotope ratio mass spectrometry that enables the differentiation between endogenous and exogenous sources. The comparison of d-values obtained from endogenously produced steroids independent from testosterone and its metabolism with urinary testosterone and its metabolic products allow the determination of surreptitious applications.
[Back to top] Liquid Chromatographic- Mass Spectrometric Methods for
the Analysis of Persistent Pollutants: Polycyclic Aromatic Hydrocarbons,
Organochlorine Compounds and Perfluorinated Compounds
H. Moriwaki
Liquid chromatography coupled with mass spectrometry (LC/MS) has become an invaluable technique for trace analysis of pollutants in the environment. Use of this technique offers a faster, more convenient, and more sensitive way to analyze many environmental pollutants. Of these, persistent pollutants in environment, some of which elicit toxicities, are monitored extensively in various environmental matrices as they are known to accumulate biologically through the food chain. Using LC/MS for the analysis of persistent pollutants has the potential to contribute to the simplification of analytical methods and the enhancement of sensitivity. This article presents a review of LC/MS methods published thus far on the determination of polycyclic aromatic hydrocarbons, organochlorine compounds and perfluorinated acids.
[Back to top] Liquid Chromatography Tandem Mass Spectrometry as a Tool
to Investigate Pesticides and Their Degradation Products
Claudio Medana, Paola Calza, Claudio Baiocchi and Ezio Pelizzetti
The analytical determination of organic structures is a fundamental need in environmental, food and medicinal chemistry, and the chemistry of pesticide compounds is closely involved in this determination because of the environmental and biological transformations that can occur to these molecules. Degradation products often possess higher toxicity than parent substances but unknown structures, and aqueous milieu produce hard-to-solve instrumental problems. The need to analyze low concentrations in polar solutions means that methods in which liquid chromatography is hyphenated to mass spectrometry have a large playing field, which combines trace determination and structural elucidation. An important area of study comprises degradation-simulating models, such as titanium dioxide mediated photocatalytic attacks on different organic structures. HPLC-mass spectrometric studies on pesticides, their metabolites and their degradation products are reviewed.
[Back to top] Functional
Protein Analysis Using Mass Spectrometry
Simone Konig
Mass spectrometry is a very versatile technique which has become both a high-throughput and a research tool in the biosciences. In this review, methods of functional protein analysis are discussed from a perspective in clinical research. The basics of proteomics is introduced as well as the determination of post-translational modifications such as phosphorylation. The investigation of protein interactions involves the measurement of non-covalent complexes and small molecule ligands as well as bioaffinity mass spectrometry. Comparative analysis of sample profiles on specific surfaces is performed increasingly to distinguish disease-related changes.
[Back to top] Overview
of Common Spectroscopic Methods to Determine the Orientation/Alignment of
Membrane Probes and Drugs in Lipidic Bilayers
Sílvia C. D. N. Lopes and Miguel A. R. B. Castanho
The in-depth location and orientation of membrane probes and drugs inserted in lipidic bilayers are regarded important key-properties that cannot be overlooked during molecular design and synthesis. Several spectroscopic phenomena (e.g. excitonic interaction) and molecular recognition (e.g. ligand-receptor interaction) depend on these properties. However, molecular orientation in lipidic membranes is scarcely addressed. This paper overviews some of the most important techniques and methodologies used to study orientation of molecules relative to the surrounding lipidic matrix, namely: FTIR linear dichroism, UV-Vis linear dichroism, Time-resolved fluorescence anisotropy, NMR, and Surface Plasmon Resonance.
[Back to top] Analysis
of Biological Macromolecular Assemblies Using Static Light Scattering Methods
LeAnn J. Godderz, Mandy M. Peak and Karla K. Rodgers
Multi-angle laser light scattering (MALLS) is a valuable spectroscopic technique that can give the absolute mass of macromolecules, independent of molecular shape. When coupled with size exclusion chromatography (SEC), individual components may be separated into fractions before analyses by MALLS, thus yielding the absolute molecular mass of each species. This review covers the technical background for MALLS-SEC as well as several examples of its application from our own work. We have utilized MALLS-SEC to investigate the protein-protein and protein-DNA interactions of the VDJ recombinase. The recombination activating gene products (RAG1 and 2) form the VDJ recombinase and catalyze the initial DNA cleavage steps during V(D)J recombination, the mechanism primarily responsible for diversification of the immune response. Through MALLS-SEC analysis of the RAG proteins, we have determined the self-association properties of RAG1, investigated ionic interactions in oligomerization, and performed kinetic studies of oligomerization over time. In addition, we have analyzed the oligomerization of RAG1 in the presence of its target DNA, the recombination signal sequence. Finally, we provide an overview of the current applications of MALLS-SEC from recent literature, which illustrates the scope of MALLS-SEC as a powerful technique for determining the biophysical properties of macromolecules.
[Back to top] Biological
Imaging and Spectroscopy of pH
Valery V. Khramtsov
The critical role of pH status in physiology and pathophysiology of living organisms is well recognized. This includes local acidosis induced by ischemia, infection or inflammation, extracellular acidosis in tumors, depth-specific tissue pH variations during skin treatments or wound healing, etc. At the microscopic scale local pH drastically affects the vital activities of cell, cellular organelles and enzymes. Upon therapeutic intervention, the delivery, absorption and pharmacological effectiveness of drugs can be altered by changing the pH of their local environment. Therefore, spatially and temporarily addressed pH measurements in vivo are of considerable clinical relevance. At subcellular levels, spatiotemporal pH assessment provides significant insight into the mechanisms of pH regulation in cellular organelles and its role in cellular signaling including cell proliferation and apoptosis.
Current methods in biological pH detection and imaging, their limits, advantages and recent applications, as well as further perspectives of their development are discussed. Non-invasive spectroscopic approaches mostly rely on endogenous or/and exogenous molecular probes that are weak acids or bases with pH-dependable spectral properties. Absorption and fluorescent probes may be considered particularly effective for pH studies on cellular and subcellular levels, while magnetic resonance approaches based on EPR and NMR spectroscopies have the advantage for in vivo applications in animals and humans. Special emphasis is given to EPR spectroscopy due to the rapid development of lowfield EPR techniques and new pH sensitive probes with enhanced spectral properties making in vivo pH detection and imaging possible.