磷脂Phospholipid

甘油磷脂以磷脂酸为母体，磷酸再与胆碱、乙醇胺、丝氨酸或肌醇结合，分别得到磷脂酰胆碱（卵磷脂）、磷脂酰乙醇胺、磷脂酰丝氨酸和磷脂酰肌醇。两条疏水尾避开水、亲水头朝向水，使磷脂在水中形成双层膜、脂质体或胶束，这一过程由疏水效应驱动。膜的流动性取决于脂肪酸链的长度、不饱和度和胆固醇含量。

Glycerophospholipids derive from phosphatidic acid, whose phosphate is joined to choline, ethanolamine, serine or inositol to give phosphatidylcholine (lecithin), phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. With hydrophobic tails avoiding water and hydrophilic heads facing it, phospholipids form bilayers, liposomes or micelles, driven by the hydrophobic effect. Membrane fluidity depends on chain length, unsaturation and cholesterol content.

1847 年法国化学家戈布利从蛋黄中分离出卵磷脂，名称来自希腊语“蛋黄”（lekithos）。1925 年戈特和格伦德尔用红细胞脂质在水面铺成单分子层，面积约为细胞表面积的两倍，推断细胞膜是脂双层。1965 年班厄姆发现磷脂在水中形成封闭囊泡，后称脂质体。

In 1847 the French chemist Gobley isolated lecithin from egg yolk, naming it from the Greek lekithos, yolk. In 1925 Gorter and Grendel spread red-cell lipids as a monolayer on water and found it covered about twice the cell surface area, concluding that the membrane is a lipid bilayer. In 1965 Bangham found that phospholipids form closed vesicles in water, later called liposomes.

磷脂构成细胞膜和细胞器膜；磷脂酰肌醇被磷脂酶 C 水解生成 IP₃ 和二酰甘油两种第二信使；肺表面活性物质（二棕榈酰磷脂酰胆碱）降低肺泡表面张力。工业上大豆卵磷脂用作食品乳化剂；脂质纳米粒是 mRNA 疫苗的递送载体，脂质体用于包载抗癌药物。

Phospholipids form the membranes of cells and organelles; phospholipase C splits phosphatidylinositol bisphosphate into two second messengers, IP₃ and diacylglycerol; lung surfactant (dipalmitoylphosphatidylcholine) lowers surface tension in the alveoli. Soy lecithin is a food emulsifier, lipid nanoparticles deliver mRNA vaccines, and liposomes carry anticancer drugs.