E-Book, Englisch, 612 Seiten, Format (B × H): 152 mm x 229 mm
Ridgway / McLeod Biochemistry of Lipids, Lipoproteins and Membranes
6. Auflage 2015
ISBN: 978-0-444-63449-8
Verlag: Elsevier Science & Technology
Format: EPUB
Kopierschutz: 6 - ePub Watermark
E-Book, Englisch, 612 Seiten, Format (B × H): 152 mm x 229 mm
ISBN: 978-0-444-63449-8
Verlag: Elsevier Science & Technology
Format: EPUB
Kopierschutz: 6 - ePub Watermark
Biochemistry of Lipids: Lipoproteins and Membranes, Volume Six, contains concise chapters that cover a wide spectrum of topics in the field of lipid biochemistry and cell biology. It provides an important bridge between broad-based biochemistry textbooks and more technical research publications, offering cohesive, foundational information.
It is a valuable tool for advanced graduate students and researchers who are interested in exploring lipid biology in more detail, and includes overviews of lipid biology in both prokaryotes and eukaryotes, while also providing fundamental background on the subsequent descriptions of fatty acid synthesis, desaturation and elongation, and the pathways that lead the synthesis of complex phospholipids, sphingolipids, and their structural variants. Also covered are sections on how bioactive lipids are involved in cell signaling with an emphasis on disease implications and pathological consequences.
- Serves as a general reference book for scientists studying lipids, lipoproteins and membranes and as an advanced and up-to-date textbook for teachers and students who are familiar with the basic concepts of lipid biochemistry
- References from current literature will be included in each chapter to facilitate more in-depth study
- Key concepts are supported by figures and models to improve reader understanding
- Chapters provide historical perspective and current analysis of each topic
Autoren/Hrsg.
Fachgebiete
Weitere Infos & Material
Chapter 1. Structure and function of membranes
Chapter 2. Fatty acid and phospholipid metabolism in prokaryotes
Chapter 3. Fatty acid and lipid metabolism in plants
Chapter 4. Fatty acid synthesis in eukaryotes.
Chapter 5. Fatty acid elongation and desaturation.
Chapter 6. Fatty acid oxidation
Chapter 7. Phospholipid synthesis in eukaryotes
Chapter 8. Intra-and inter-membrane lipid transport
Chapter 9. Structure function of ether lipids
Chapter 10. Phospholipid catabolism
Chapter 11. The eicosanoids
Chapter 12. Sphingolipids
Chapter 13. Cholesterol synthesis
Chapter 14. Bile acid metabolism
Chapter 15. Lipid modification of proteins
Chapter 16. Lipoprotein structure and metabolism
Chapter 17. Triglyceride-rich lipoproteins
Chapter 18. Lipoprotein receptors
Chapter 19. Atherosclerosis.
Chapter 20. Obesity and diabetes.
Chapter 21. Methods of lipid analysis
Chapter 2 Approaches to Lipid Analysis
Jeff G. McDonald1, Pavlina T. Ivanova2, and H. Alex Brown2,3 1Department of Molecular Genetics, UT Southwestern Medical Center, Dallas, TX, USA 2Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA 3Department of Biochemistry and The Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, USA Abstract
Historically, lipids have been defined in many ways, but at the most elementary level, they are biologically derived molecules soluble in organic solvents. Lipid species include chemical entities that are among the fundamental building blocks of life. The chemical and structural heterogeneity of lipids contributes to innumerable biochemical and biophysical processes and thereby presents challenges in analysis. Advances in chromatography, mass spectrometry and computational biology have enabled the progression of lipidomics within the larger field of analytical chemistry. Advancements in mass spectrometry-based lipid analysis have contributed to remarkable discoveries in both basic and translational research and any well-conducted study of biological processes involving lipids is now expected to include lipidomic analysis. In this chapter we introduce readers to the basic concepts of identification and measurements of lipid species that constitute the modern field of lipidomics. Keywords
Lipidomics; Mass spectrometry; Phospholipids; Sterols Abbreviations EI Electron ionisation GC Gas chromatography HPLC High-performance liquid chromatography LLE Liquid–liquid extraction MS Mass spectrometry NIST National Institute of Standards and Technology TAG Triacylglycerol TLC Thin-layer chromatography RRF Relative response factor TMAO Trimethylamine-N-oxide 1. Introduction and Overview
Lipids are among the fundamental building blocks of life. Simple ancient organisms living in the preoxidising environment likely used hydrocarbon chains and pentacyclic ring sterol-like compounds to evolve the huge diversity of complex structures that constitute the rich array of fats found throughout the tree of life. These molecules have remarkable chemical and structural heterogeneity that contributes to innumerable biochemical and biophysical processes. That organic oils (a mixture of chemicals composed largely of fatty acids and triacylglycerols (TAGs)) are precious and valuable commodities have been recognised by humans for thousands of years. This value justifies the classification and careful measurement of these compounds. The analysis of lipids by mass spectrometry (MS) has been performed for decades, but a systems biology-based analysis that monitors changes in many lipid analytes in parallel has its beginnings in the early part of the current century. As elegantly defined by McLafferty and Turecek (1993), ‘The mass spectrum shows the mass of the molecule and the masses of the pieces from it’. This is the fundamental basis for the analysis of lipids by MS just as for other small molecule analytes. The mass spectrum of a lipid does not reveal the precise chemical structure of the molecular species, but its systematic fragmentation gives information about the chemical arrangement. For precise determination of the structures of unknown lipids, a combination of MS with other techniques, such as nuclear magnetic resonance, is required. 2. Lipid Diversity
Lipids have many definitions but, in simplest terms, are biologically relevant molecules that are soluble in organic solvents (major lipid classes and their metabolic origins are shown in Figure 1). They include a wide variety of chemical entities such as fatty acids and their derivatives, sterols and steroids and isoprenoids. Fatty acid moieties can be esterified to alcohols, forming glycerol-based lipids like TAGs (Chapters 5 and 6), or be linked by an amide bond to long-chain bases, forming sphingolipids (Chapter 10). Each of these lipids can also contain phosphoric acid, forming the phospholipid category (Chapters 3 and 7). Some lipids are a source of energy in biological systems, while others serve as building blocks and major participants in cellular recognition and signal transduction across the cell membrane. This vast diversity in structure reflects the unique amphiphilic property of lipids imparted by their hydrophobic acyl chains and hydrophilic head groups. Lipids can generally be divided into three categories – fatty acids, simple lipids and complex lipids. Fatty acids from plant and animal origin have different properties. Fatty acids of animal origin are summarised in several subcategories – cis/trans, saturated, mono- or polyunsaturated. Plant fatty acids are more complex and may contain different functionalities, including epoxy-, hydroxy- and keto- groups. Bacterial fatty acids can contain branched, odd-carbon or cyclopropane groups (the synthesis and metabolism of these fatty acids is described in Chapters 3–6). Simple lipids only contain fatty acids and alcohol constituents. The alcohol can be glycerol, esterified on one, two or all three hydroxyl groups, sterols or a long-chain alcohol. They are represented in triacyl-, diacyl- or monoacylglycerols, cholesterols and cholesteryl esters and wax esters. Complex lipids include glycoglycerolipids, glycerophospholipids and sphingolipids that are the major phospholipids present in mammalian cells. The comprehensive analysis of lipids generally involves separation into simpler categories, according to their chemical nature and identification and eventual quantitative measurement of a specific class, subclass or individual lipid (Hanahan, 1997).
Figure 1 Human lipid diversity. Relationships among the major mammalian lipid categories are shown starting with the 2-carbon precursor acetyl-CoA, which is the building block in the biosynthesis of fatty acids. Fatty acyl substituents in turn are transferred to be part of the complex lipids, namely sphingolipids, glycerolipids, glycerophospholipids and sterols (as sterol esters). Fatty acids are also converted to eicosanoids. A second major biosynthetic route from acetyl-CoA generates the 5-carbon isoprene precursor isopentenyl pyrophosphate, which provides the building blocks for the prenol and sterol lipids. Fatty acyl-derived substituents are coloured green; isoprene-derived atoms are coloured purple; glycerol and serine-derived groups are coloured orange and blue, respectively. Arrows denote multistep transformations among the major lipid categories starting with acetyl-CoA. This figure and legend are modified from the original that appeared in Quehenberger et al. (2010), © the American Society for Biochemistry and Molecular Biology. 3. Chromatographic-Based Analysis of Lipids
3.1. Historical Perspective
The identification of lipids by chemical analysis dates back more than two centuries. Excellent timelines and historical perspectives of lipid science can be found throughout this book and elsewhere on the development of MS-based techniques (Brügger et al., 1997; Ivanova et al., 2001; Murphy et al., 2001; Han and Gross, 1995; Brown and Murphy, 2009). Detailed reports of methodologies for lipid measurements can be found dating back more than a century. These include the first mention of colourimetric assays, column chromatography and thin-layer chromatography (TLC). The introduction of spectrophotometric techniques provided additional insight for lipid researchers. Although modern versions of these tools are still employed in today’s laboratories, there have been considerable advances made in the quantitative measurement of lipids. Advances in chromatography, the advent of modern electronics (especially computers) and breakthroughs in gas-phase ionisation have dramatically expanded the tools for lipid analysis. A detailed explanation of the technical aspects of lipid MS from one of the pioneers of the lipid biochemistry field, Robert Murphy (1993), provides insightful explanations of collision-induced dissociation, ionisation techniques and other important details for the analysis of major lipid classes as well as interesting comments regarding the history and development of lipid analysis by MS. 3.2. Lipid Extraction from Biological Sources
Extraction of lipids from biological samples (e.g. cells, tissues, fluids) is the first step in any lipid analysis. An extraction begins when organic solvents are used to solubilise and separate the lipids from proteins, which are largely insoluble in these solvents. If necessary, the choice of extraction solvent can be tailored to a specific class of lipids (e.g. sphingolipids, phospholipids, lysophospholipids, phosphoinositides). In addition to solubilising lipids, solvents can serve to inactivate enzymes and denature proteins that would otherwise degrade or modify the extracted lipids. Solvent extraction will also help minimise the oxidation of polyunsaturated fatty acids. For these reasons, lipids are typically extracted from fluids, tissues or cultured cells soon after their removal or isolation....
