Lipid structural elucidation

The exact structural and spatial characterization of the lipids is still very limited, particularly in routine determination of lipids. As an example, routine determination of snl/sn2 acyl positions in PLs is not possible, nor is the determination of positions of double bonds or acyl chain branching. Such information would be important to understand the data in the biochemical context (e.g., affinity for specific lipid enzymes). While promising efforts are under way, it may still take time before the emerging tools for lipid structural elucidation are introduced in routine lipidomic analyses. Big advances have also been made over the past years in the developments of methods for surface analysis of lipids. These approaches will be crucial for in-depth elucidation of the spatial complexity of cellular and subcellular lipidomes. 

B. Lindner, U. Zahringer, E. Th. Rietschel, and U. Seydel, in A. Fox, S. L. Morgan, L. Larsson, and G. Odham (Eds.), Analytical Microbiology Methods Structural Elucidation of Lipopolysaccharides and Their Lipid A Component Application of Soft Ionization Mass Spectrometry, p. 149. Plenum, New York/London, 1990. 

In this experiment we will approach the world of lipids with an introduction to analytical procedures currently applied to lipid extraction, purification, characterization, and structure elucidation. 

Gigg J, Gigg R, Payne S, Conant R (1986) Synthetic studies on the major serologically active glycolipid from Mycobacterium leprae, in Klein RA, Schmitz B (eds) Topics in lipid research — from structural elucidation to biological function, Royal Society of Chemistry p. 119... 

H Tomoda, I Namatame, N Tabata, K Kawaguchi, S Si, S Omura. Structure elucidation of fungal phenochalasins, inhibitors of lipid droplet formation in mouse macrophages. J Antibiot 52 857-861, 1999. 

David Morgan is a member of the Chemical Ecology Group at Keele University. He was bom in Newfoundland and had his university education there, at Dalhousie University and University of King s College in Halifax, Nova Scotia, and at Oxford. His doctorate thesis was on the lipids of Mycobacterium tuberculosis. He later worked at the National Institute for Medical Research in London, and for Shell Chemical Company and Shell Research under the direction of Sir Robert Robinson, O.M., Nobel Laureate. From 1966 he has been at Keele in Staffordshire as lecturer, senior lecturer, reader, and professor. He discovered the natural pesticide azadirachtin and collaborated with S. V. Ley for its final structure elucidation. He is the author of over 300 papers and reviews, mostly on insect chemistry, editor, and contributor to several volumes and author of the book Biosynthesis in Insects. ... 

Gibbons, W. A., Hughes, R. A., Charalambous, M., et al. (1990) Synthesis, resolution and structural elucidation of lipidic amino acids and their homo- and hetero-oligomers. Liebigs Ann. Chem. 12, 1175-1183. 

H.Kuhn, J.Belkner, R.Wiesner, T.Schewe, V.Lankin and A.Tikhaze, Structure elucidation of oxygenated lipids in human atherosclerotic lesions, Eicosanoids 5 (1992) 17-22. 

Simon, G. and G. Rouser. 1967. Phospholipids of the sea anemone Quantitative distribution absence of carbon-phosphorus linkages in glycerol phospholipids structural elucidation of ceramide aminoethylphophonate. Lipids 2 55. 

Prior to structural elucidation and possible eventual synthesis, the isolation of component phenolic lipids in a pure state is essential. The cold methods of thin layer chromatography (TLC), column chromatography (CC), flash chromatography, high performance liquid chromatography (HPLC) and hot methods (GC), often after derivatisation, are well established. Argentation versions of these separatory methods are less common but are desirable for the rapid separation of unsaturated constituents. 

Synthesis has often followed structural elucidation of a phenolic lipid to complete the characterisation process. However it may also become of greater significance in the study of biological properties, particularly in the involvement of structure/activity relationships. 

---