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LIPIDS I by Moazzam.pptx

  1. Moazzam Ali Shahid Senior Lecturer (Molecular Medicine) Senior Research Officer (Research) PhD Scholar (Biochemistry)
  2.  Classification ◦ Simple ◦ Complex ◦ Derived  Nomenclature  Properties  Biomedical importance
  3.  The lipids are a heterogeneous group of compounds, including fats, oils, steroids, waxes, and related compounds, which are related more by their physical than by their chemical properties.  Most membrane lipids are amphipathic, having a non-polar end and a polar end.
  4. They have the common property of being relatively ◦ Insoluble in water and ◦ soluble in nonpolar solvents such as ether and chloroform and acetone  Lipids include ◦ Triacylglycerols, phosphodiacylglycerols, sphingolipids, glycolipids, lipid-soluble vitamins, and prostaglandins ◦ cholesterol, steroid hormones, and bile acids
  6. Esters of fatty acids with various alcohols. A. Fats: Esters of fatty acids with glycerol. Oils are fats in the liquid state. B. Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols
  7.  Structure: ◦ glycerol (3C alcohol) + fatty acid dehydration synthesis  fatty acid = long HC “tail” with COOH group at “head” enzyme
  8. Nomenclature
  9. Saturated acids end in -anoic, eg, octanoic Unsaturated acids with double bonds end in -enoic, eg, octadecenoic acid (oleic acid).
  10. Some fatty acids and their common names: 14:0 myristic acid; 16:0 palmitic acid; 18:0 stearic acid; 18:1 cisD9 oleic acid 18:2 cisD9,12 linoleic acid 18:3 cisD9,12,15 a-linonenic acid 20:4 cisD5,8,11,14 arachidonic acid 20:5 cisD5,8,11,14,17 eicosapentaenoic acid (an omega-3) Double bonds in fatty acids usually have the cis configuration. Most naturally occurring fatty acids have an even number of carbon atoms. C O O 1 2 3 4 a   fatty acid with a cis-D9 double bond
  11. There is free rotation about C-C bonds in the fatty acid hydrocarbon, except where there is a double bond. Each cis double bond causes a kink in the chain. Rotation about other C-C bonds would permit a more linear structure than shown, but there would be a kink. C O O 1 2 3 4 a   fatty acid with a cis-D9 double bond
  12. 18:0 stearic acid; 18:1 cis*9 oleic acid 18:3 cisD9,12,15 a-linonenic acid