Chapter 3 Lipids Chemistry 脂类化学

1. Chapter 3Lipids Chemistry脂类化学 生物化学教研室 吴映雅 Tel:13312892168

2. 一、Definition 脂类概念 Lipids are non-polar (hydrophobic) compounds which can be soluble in organic solvents. 脂类是脂酰甘油Acylglycerol和类脂lipoid的总称。

3. 二、共同特性： 1、不溶于水，溶于乙醚aether、氯仿chloroform、苯benzene及丙酮acetone等有机溶剂； 2、具有酯ester的结构，或具有成酯的可能性； 3、可被机体所利用。

4. An ester forms when a hydroxyl reacts with a carboxylic acid, with loss of H2O.

6. Each glycerophospholipid includes • a polar region: glycerol, carbonyl羰基O of fatty acids, Pi, & the polar head group (X) • non-polar hydrocarbon tails of fatty acids (R1, R2).

7. Fatty acids脂肪酸 • Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end. • A 16-C fatty acid: CH3(CH2)14-COO- • Non-polar polar • A 16-C fatty acid with one cis double bond between C atoms 9-10 may be represented as 16:1 cis D9.

8. Most naturally occurring fatty acids have an even number of carbon atoms. Double bonds in fatty acids usually have the cis configuration.

9. Some fatty acids and their common names: 14:0myristic acid肉豆蔻酸; 16:0 palmitic acid棕榈酸/软脂酸; 18:0stearic acid硬脂酸; --------------saturated fatty acids 饱和脂肪酸

10. 不饱和脂肪酸unsaturated fatty acids 18:1 cisD9 oleic acid油酸 18:2 cisD9,12 linoleic acid亚油酸 18:3 cisD9,12,15a-linonenic acid亚麻酸 20:4 cisD5,8,11,14 arachidonic acid花生四烯酸（20个C、是前列腺素的前体） 20:5 cisD5,8,11,14,17 eicosapentaenoic acid二十碳五烯酸(an omega-3) 亚油酸、亚麻酸、花生四烯酸等称必需脂肪酸

11. Naming of fatty acids C18    10 9 CH3-(CH2)7-CH=CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH Cis 9 18:0, stearic acid : octadecanoic acid 18:1 (9), oleic acid : octadecenoic acid 18:2 (9,12), linoleic acid : octadecadienoic acid (-6) 18:3 (9,12,15), -linolenic acid : octadecatrienoic acid (-3)

12. Essential Fatty Acids Omega-3 (ω-3) and omega-6 (ω-6) fatty acids are unsaturated "Essential Fatty Acids" . The two EFAs are linolenic (ω-3) and linoleic (ω-6). The “3" and “6" indicate where the first double bond occurs in the fatty acid molecule. Example: DHA (docosahexenoic acid, C22:6 ) and AA (arachidonic acid, C20:4) are both crucial to the optimal development of the brain and eyes. Health consideration: In modern diets: ω-6 / ω-3 ratio = 15:1; Expected ratio: 2:1 to 4:1 reduced mortality from cardiovascular disease, suppressed inflammation in patients with rheumatoid arthritis (风湿性关节炎), and decreased risk of breast cancer.

13. 类花生酸eicosanoid • 由花生四烯酸合成，调节细胞代谢，与炎症、免疫、过敏、心血管疾病有关 • （一）前列腺素prostaglandin：平滑肌松弛或收缩等广泛生理功能 • （二）血栓素thromboxane：凝集血小板和血栓形成 • （三）白三烯leukotrienes：调节白细胞、凝集血小板等等

14. The Nobel Prize in Physiology and Medicine 1982 "for their discoveries concerning prostaglandins and related biologically active substances" Bengt I. Samuelsson John R. Vane Sune K. Bergström Sweden United Kingdom Sweden b.1927 b.1916 b.1934

15. 甘油酯类： 脂酰甘油 acylglycerol脂肪 glyceride磷酸甘油酯phosphoglyceride 神经鞘磷脂sphingomyelin 神经鞘脂类 脑苷脂cerebroside sphingolipid 神经节苷脂ganglioside (含唾液酸sialic acid） 类脂 类固醇： 胆固醇cholesterol steroid胆固醇酯cholesterol ester 胆汁酸bile acid 类固醇激素steroid hormone。 磷脂 糖脂 三、分类(classification) 按化学结构分：按生理功能分：

16. 甘油酯glyceride • They have a glycerol backbone. • Hydroxyls in glycerol are esterified酯化 to fatty acids.

17. 鞘脂类sphingolipid • 鞘氨醇sphingol/sphigolsine结构 Sphingolipids are derivatives of the lipid sphingosine, which has a long hydrocarbon tail, and a polar domain that includes an amino group.

18. 类固醇steroid • 环戊烷多氢菲结构

19. 第二节 甘油酯类(glycerides) （一）脂酰甘油acylglycerol 甘油+脂肪酸酯 按被酯化的-OH数目不同，可分为： 单酰甘油monoacylglycerol 二酰甘油diacylglycerol 三酰甘油triacylglycerol 含甘油glycerol结构

20. Triacylglycerols 三酰甘油 Structure: TAGs are fatty acid esters of glycerols, with each TAG made up of 1 glycerol and 3 FAs.

21. O O O CH2 O C R1 CH O C R2 CH2 O C R3 三酰甘油(triacylglycerol, triglyceride)结构： 脂肪性质：水解hydrolyze、皂化saponify、氢化hydrogenate、碘化’iodinate、酸败rancidify 植物油：含不饱和(脂肪酸多，熔点低，在室温时为液体-----称“油oil” 动物油：含饱和脂肪酸多，熔点高，在室温时为固体，称“脂”、“脂肪fat”

22. 第三节 磷酸甘油酯、甘油磷脂phosphoglycerides、glycerophospholipid： O CH2 O C R1 O R2 C O CH O CH2 O P OH OH X X 磷脂酸结构示意图： ：胆碱(choline )、乙醇胺(ethanolamine )、丝氨酸(serine)、肌醇(inositol )、甘油磷脂酸

26. Glycerophospholipids(phosphoglycerides磷酸甘油酯), are common constituents of cellular membranes. They have a glycerol backbone. Hydroxyls at C1 & C2 are esterified to fatty acids. Glycerophospholipids甘油磷脂

27. Phosphatidate磷脂酸 In phosphatidate: • fatty acids are esterified to hydroxyls on C1 & C2 • the C3 hydroxyl is esterified to Pi.

28. In most glycerophospholipids (phosphoglycerides), Pi is in turn esterified to OH of a polarhead group (X): e.g., serine丝氨酸, choline胆碱, ethanolamine乙醇胺, glycerol, or inositol肌醇. The 2 fatty acids tend to be non-identical. They may differ in length and/or the presence/absence of double bonds.

29. Phosphatidylinositol磷脂酰肌醇, with inositol as polar head group, is one glycerophospholipid. In addition to being a membrane lipid, phosphatidylinositol has roles in cell signaling.

30. Phosphatidylcholine, with choline as polar head group, is another glycerophospholipid. It is a common membrane lipid.

31. 磷酸甘油酯作用 1、磷脂酰胆碱 phosphatidyl choline： 卵磷脂lecithin ,在蛋黄中含量很高 1)构成生物膜cell membrane、神经组织nerve tissue的重要成分 2)协助脂肪运输fat transportation 2、磷脂酰乙醇胺phosphatidyl ethanolamine : (脑磷脂cephalin) 在脑、神经组织组织中含量高。 X：胆碱、乙醇胺、丝氨酸、肌醇、甘油磷脂酸

32. 神经鞘脂类(sphingolipid ) 神经鞘氨醇(或二氢神经鞘氨醇)+脂肪酸， 1．神经鞘磷脂(sphingomyelins )： 组成生物膜的重要成分，在脑、神经组织中含量高。 2．脑苷脂(cerebrosides)： 在神经髓鞘中含量多。 鞘糖脂 3. 神经节苷脂(gangliosides )： 脑灰质中含量最高，参与神经传导，与细胞免疫、细胞识别相关。

33. 糖脂 糖脂glycolipid鞘糖脂 glycosphingolipid 甘油糖脂glyceroglycolipid 作用： 细胞膜结构成分，脑、神经髓鞘成分，构成血型物质，膜抗原

34. HO 第四节 类固醇 胆固醇(cholesterol)结构

35. 类固醇激素steroid hormone（甾类激素） （一）肾上腺皮质激素adrenocortical hormone, cortin 盐皮质激素：如醛固酮 糖皮质激素：如皮质醇（氢化可的松） （二）性激素sex hormone 雄性激素male hormone 雌性激素female hormone雌激素estrin 孕激素progestogen