第三章磷脂
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Chapter 3 Lipids and Membranes
3.1 Introduction
3.1.1 The concept of lipid Lipids are the esters and their derivatives formed by lipid acids and alcohol Lipid (also called lipids) are low-soluble in water and highly soluble in non-polar organic solvents This quality is called fat soluble(脂溶性 ).
甘油
脂肪酸
三酰甘油
R1、R2、R3相同，称为单纯甘油酯，R1、R2、R3有2 个或3个不同，称为混合甘油酯， 如果R1 、R3 不相同，则中间的碳原子为不对称碳原 子，其上羟基所成的酯在左边的为L-型，在右边的为 D-型。
3.2.2 Fatty acid
COOH
COOH
Fatty acid is an organic carboxylic acid, containing 1 long hydrocarbon chain (alkyl烃基) and a carboxyl(羧基) end group C12～C20, high fatty acid Saturated FA: sloid state Palmitic acid 软脂酸(16- carbonate) :C15H31COOH Stearic acid 硬脂酸(18 - carbonate): C17H35COOH Unsaturated FA: liquid state; oleic acid
Membranes: ~25-50% lipid and 50-75% proteins Simple function: higher content of lipids Complex function: higher content of protein Lipids: mainly phospholipids, glycolipid and sterol
Iodine number
N × V1 − V2） 127 × 2 / 1000 （ × 碘值 = × 100 W
式中：V1 空白实验（不加油脂）用去的硫代硫酸 钠的毫升数； V2为滴定时用去的硫代硫酸钠的毫升数； N为硫代硫酸钠的浓度； 127为碘的相对原子质量； W为样品油脂质量。 碘值越大，说明油脂中所含的不饱和脂肪酸数越 多，油脂的不饱和程度越大。
3.2 Fat
3.2.1 Structure of Fat Sturcture ： the most common fat is triacylglycerol, i.e., the ester formed by 1 molecule glycerol and 3 molecule fatty acids
Natural fat could generate odour after the exposure in the air , which is called 酸 败 (rancidity)。 reason： ① 脂类 脂肪酸 ② 脂类 醛、酮 过氧化物, 继续分解产生低级醛、酮，羧酸和 醛或酮的衍生物，这些物质使油脂产生臭味。
Amphiphilic structure of Phospholipids
N+ CH2 CH2 O O P O CH2 CH O C R1 CH2 O OC R2 O O(CH3)3
Polar head
Non-polar tail
Lipid bilayer
Nonpolar tails point toward the interior. Polar head groups contact aqueous medium. Phospholipids in the aqueous phase can be spontaneously formed lipid bilayer. Lipid bilayersare the structural basis for all biological membranes.
3.1.2 Classification of lipid
According to different chemical composition ： Simple lipid(单脂): Triglyceride(甘油三酯 ) ，wax Complex lipid(复脂): Glycerol phospholipids(甘 油磷脂), glycolipid(糖脂), lipoprotein(脂蛋白). Derived lipid: Steroids类固醇, Vitamin A、D、E、 K
3.2.2 Properties of fat
Physical properties ： Colorless, tasteless Lighter than water, they are difficult to dissolve in water, soluble in organic solvents no constant melting point and boiling point
3.3.1.2 Sphingomyelin 鞘磷脂
鞘磷脂大量存在于神经组织和脑内，因此常称为神 经鞘磷脂，它是脑与神经细胞膜的重要成分。 鞘磷脂分子是由磷酸、脂肪酸、胆碱以及鞘氨醇组 成的，它只有1个脂肪酸分子。
3.3.2 Sterol
菲
环戊烷多氢菲
ห้องสมุดไป่ตู้
甾
固醇类是环戊烷多氢菲的衍生物，在有机溶剂中容易 结晶出来，并且它具有高级脂肪醇的性质，因此称为 固醇。 各种固醇物质都具有上述共同的骨架，差别只是在B 环中的双键位置，双键数目，以及C17上侧链的结构不 同.
Phosphatidate 甘油磷脂
磷脂酸
甘油磷脂
Phosphatidate
1. Two carbon atoms become hydrophobicity through esterification of the fatty acids: 2 molecular non-polar tail 2. The third of carbon atoms by phosphate, and with a hydrophilic such as the Xcholine, cholamine and other groups, has become the hydrophilic : The first one molecular polarity 3. Amphiphilic 两性 compounds
皂化值=V×N×56.1/W 式中：V为测定皂化值时滴定HCl的毫升数（空白 减去样品）； N为HCl的浓度； 56.1为KOH的分子量； W为测定时所用油脂的质量。 从皂化值的大小可推知脂肪中所含脂肪酸的平均分 子量，油脂的皂化值与平均分子量成反比。
Emulsification乳化作用
酸败作用rancidity
C3H5 (OCOR)3 + 3H2O → 3RCOOH+ C3H5(OH)3 脂肪 脂肪酸 甘油 RCOOH + NaOH → RCOONa + H2O 脂肪酸 肥皂
Saponification number
Saponification number: 1g fat saponification refers to the necessary number of mg of KOH
Iodine number(碘值)
Unsaturated fatty acids can happen addition reaction with hydrogen or halogen to form saturated fatty acid. The addition reaction of fatty acid with halogen is called halogenation (卤化作用), which is used to deduce the unsaturated degree of fatty acid in fat. Iodine number 碘值:100g fat absorption by the number of grams of iodine
3.4 Biomembrane 生物膜
Biomembrane is an umbrella term for all membranes (films), including all cell membrane and cell organ membranes.
3.4.1 Composition and structural model of biomembrane
Membrane protein
The main function of biomembrane depends on the membrane protein Proteins attach to membranes in different ways. Some proteins, called integral proteins内在膜蛋 白, span the lipid bilayer. Some proteins, called peripheral proteins外在膜 蛋白, are bound to membranes loosely and reversibly.
3.1.2 Classification of lipid
According to different composition in the body:
3.1.3 Biological function of lipid
As a structural substance phospholipids is the main component of membrane. As a storage of energy As a solvent Lubricant and winterproofing agent
Saponification
脂肪 + H2O → 甘油 + 脂肪酸 The acid hydrolysis of fat is reversible, however, the alkaline hydrolysis is irreversible. The alkaline hydrolysis of saponification(皂化作用)。 fat is called
COOH
3.2.2 Fatty acid
COOH
Fatty acids (FA) differ from one another in: (1) Length of the hydrocarbon tails (2) Degree of unsaturation (double bond) (3) Position of the double bonds in the chain 脂肪酸的表示是先写出碳原子数，再写出双键数，最 后表明双键的位置。 软脂酸C16：0: 16 carbon，no double bond 亚油酸C18：2（9，12）18 carbon，2 double bonds, lie between C9 and C10, C12 and C13, respectively. 1 double bond： monoene fatty acid >2 double bond：polyene fatty acid
3.3 Phospholipids and sterol
3.3.1 Phospholipids
Phospholipids are a class of complex lipids containing phosphorous acid and are a major component of all cell membranes as they can form lipid bilayers. 3.3.1.1 phosphatidate甘油磷脂 Derivative of phosphatidic acid. glycerol 甘 油 、 fatty acid 脂 肪 酸 、 phosphorous acid 磷 酸 and alkaline compound（choline 胆碱or cholamine胆胺）.
3.1 Introduction
3.1.1 The concept of lipid Lipids are the esters and their derivatives formed by lipid acids and alcohol Lipid (also called lipids) are low-soluble in water and highly soluble in non-polar organic solvents This quality is called fat soluble(脂溶性 ).
甘油
脂肪酸
三酰甘油
R1、R2、R3相同，称为单纯甘油酯，R1、R2、R3有2 个或3个不同，称为混合甘油酯， 如果R1 、R3 不相同，则中间的碳原子为不对称碳原 子，其上羟基所成的酯在左边的为L-型，在右边的为 D-型。
3.2.2 Fatty acid
COOH
COOH
Fatty acid is an organic carboxylic acid, containing 1 long hydrocarbon chain (alkyl烃基) and a carboxyl(羧基) end group C12～C20, high fatty acid Saturated FA: sloid state Palmitic acid 软脂酸(16- carbonate) :C15H31COOH Stearic acid 硬脂酸(18 - carbonate): C17H35COOH Unsaturated FA: liquid state; oleic acid
Membranes: ~25-50% lipid and 50-75% proteins Simple function: higher content of lipids Complex function: higher content of protein Lipids: mainly phospholipids, glycolipid and sterol
Iodine number
N × V1 − V2） 127 × 2 / 1000 （ × 碘值 = × 100 W
式中：V1 空白实验（不加油脂）用去的硫代硫酸 钠的毫升数； V2为滴定时用去的硫代硫酸钠的毫升数； N为硫代硫酸钠的浓度； 127为碘的相对原子质量； W为样品油脂质量。 碘值越大，说明油脂中所含的不饱和脂肪酸数越 多，油脂的不饱和程度越大。
3.2 Fat
3.2.1 Structure of Fat Sturcture ： the most common fat is triacylglycerol, i.e., the ester formed by 1 molecule glycerol and 3 molecule fatty acids
Natural fat could generate odour after the exposure in the air , which is called 酸 败 (rancidity)。 reason： ① 脂类 脂肪酸 ② 脂类 醛、酮 过氧化物, 继续分解产生低级醛、酮，羧酸和 醛或酮的衍生物，这些物质使油脂产生臭味。
Amphiphilic structure of Phospholipids
N+ CH2 CH2 O O P O CH2 CH O C R1 CH2 O OC R2 O O(CH3)3
Polar head
Non-polar tail
Lipid bilayer
Nonpolar tails point toward the interior. Polar head groups contact aqueous medium. Phospholipids in the aqueous phase can be spontaneously formed lipid bilayer. Lipid bilayersare the structural basis for all biological membranes.
3.1.2 Classification of lipid
According to different chemical composition ： Simple lipid(单脂): Triglyceride(甘油三酯 ) ，wax Complex lipid(复脂): Glycerol phospholipids(甘 油磷脂), glycolipid(糖脂), lipoprotein(脂蛋白). Derived lipid: Steroids类固醇, Vitamin A、D、E、 K
3.2.2 Properties of fat
Physical properties ： Colorless, tasteless Lighter than water, they are difficult to dissolve in water, soluble in organic solvents no constant melting point and boiling point
3.3.1.2 Sphingomyelin 鞘磷脂
鞘磷脂大量存在于神经组织和脑内，因此常称为神 经鞘磷脂，它是脑与神经细胞膜的重要成分。 鞘磷脂分子是由磷酸、脂肪酸、胆碱以及鞘氨醇组 成的，它只有1个脂肪酸分子。
3.3.2 Sterol
菲
环戊烷多氢菲
ห้องสมุดไป่ตู้
甾
固醇类是环戊烷多氢菲的衍生物，在有机溶剂中容易 结晶出来，并且它具有高级脂肪醇的性质，因此称为 固醇。 各种固醇物质都具有上述共同的骨架，差别只是在B 环中的双键位置，双键数目，以及C17上侧链的结构不 同.
Phosphatidate 甘油磷脂
磷脂酸
甘油磷脂
Phosphatidate
1. Two carbon atoms become hydrophobicity through esterification of the fatty acids: 2 molecular non-polar tail 2. The third of carbon atoms by phosphate, and with a hydrophilic such as the Xcholine, cholamine and other groups, has become the hydrophilic : The first one molecular polarity 3. Amphiphilic 两性 compounds
皂化值=V×N×56.1/W 式中：V为测定皂化值时滴定HCl的毫升数（空白 减去样品）； N为HCl的浓度； 56.1为KOH的分子量； W为测定时所用油脂的质量。 从皂化值的大小可推知脂肪中所含脂肪酸的平均分 子量，油脂的皂化值与平均分子量成反比。
Emulsification乳化作用
酸败作用rancidity
C3H5 (OCOR)3 + 3H2O → 3RCOOH+ C3H5(OH)3 脂肪 脂肪酸 甘油 RCOOH + NaOH → RCOONa + H2O 脂肪酸 肥皂
Saponification number
Saponification number: 1g fat saponification refers to the necessary number of mg of KOH
Iodine number(碘值)
Unsaturated fatty acids can happen addition reaction with hydrogen or halogen to form saturated fatty acid. The addition reaction of fatty acid with halogen is called halogenation (卤化作用), which is used to deduce the unsaturated degree of fatty acid in fat. Iodine number 碘值:100g fat absorption by the number of grams of iodine
3.4 Biomembrane 生物膜
Biomembrane is an umbrella term for all membranes (films), including all cell membrane and cell organ membranes.
3.4.1 Composition and structural model of biomembrane
Membrane protein
The main function of biomembrane depends on the membrane protein Proteins attach to membranes in different ways. Some proteins, called integral proteins内在膜蛋 白, span the lipid bilayer. Some proteins, called peripheral proteins外在膜 蛋白, are bound to membranes loosely and reversibly.
3.1.2 Classification of lipid
According to different composition in the body:
3.1.3 Biological function of lipid
As a structural substance phospholipids is the main component of membrane. As a storage of energy As a solvent Lubricant and winterproofing agent
Saponification
脂肪 + H2O → 甘油 + 脂肪酸 The acid hydrolysis of fat is reversible, however, the alkaline hydrolysis is irreversible. The alkaline hydrolysis of saponification(皂化作用)。 fat is called
COOH
3.2.2 Fatty acid
COOH
Fatty acids (FA) differ from one another in: (1) Length of the hydrocarbon tails (2) Degree of unsaturation (double bond) (3) Position of the double bonds in the chain 脂肪酸的表示是先写出碳原子数，再写出双键数，最 后表明双键的位置。 软脂酸C16：0: 16 carbon，no double bond 亚油酸C18：2（9，12）18 carbon，2 double bonds, lie between C9 and C10, C12 and C13, respectively. 1 double bond： monoene fatty acid >2 double bond：polyene fatty acid
3.3 Phospholipids and sterol
3.3.1 Phospholipids
Phospholipids are a class of complex lipids containing phosphorous acid and are a major component of all cell membranes as they can form lipid bilayers. 3.3.1.1 phosphatidate甘油磷脂 Derivative of phosphatidic acid. glycerol 甘 油 、 fatty acid 脂 肪 酸 、 phosphorous acid 磷 酸 and alkaline compound（choline 胆碱or cholamine胆胺）.