海洋动植物中不饱和脂肪酸的研究

不饱和脂肪酯是人及动物生长发育的必需物质。本论文分析了海洋动植物脂和脂肪酸的组成，并对不饱和脂肪酸的分离提纯方法进行了研究。一、海洋动植物的中性脂主要包括三酰甘油和胆固醇。动物极性脂主要为磷脂，包括磷脂酰丝馆酸（PS）、磷脂酸（PA）、磷脂酰肌醇（PI）、溶解性磷脂酰乙醇胺（LPE）、神经鞘磷脂（CAEP）、磷脂酰胆碱（PC）、磷脂酰乙醇胺（PE），双磷脂酰甘油（DPG）。其中LPE、DPG为动物所特有的磷脂。植物极性脂包括PI、PC、PE、双半乳糖苷地酰甘油酯（DGDG）、硫代6-脱氧葡萄糖苷二酰甘油酯（SQDG）、单半乳糖苷二酰甘油酯（MGDG）、磷脂酰甘油（PG）及植物脑苷脂（Plant Cerebrosides）。其中MGDG、DGDG、SQDG为植物所特有的三种糖脂。二、海洋动植物含有丰富的不饱和脂肪酸，多聚不饱和脂肪酸（PUFA）含量尤为显著。灰凹贻贝（Crenomythilus graiaynus）的二十碳五烯酸（EPA）含量为10.6%,二十碳四烯酸（AA）为3.7%，二十二碳六烯酸（DHA）为14.26%。中间球海胆（Strongylocentrotus intermedius）的AA含量为7.36%，EPA为15.98%。内枝多管藻（Polysiphonia morroωii)PUFA含量非常高，AA占2.43%，20:4ω3占4.97%，EPA占45.03%。裙带菜（Undaria pinnatifida）的PUFA中，十八碳二烯酸占6.16%，AA占12.99%，EPA占7.83%这些PUFA大都为人及动物生长发育的必需脂肪酸。三、尿素诱导法是大量提取混合PUFA的有效方法。在产品中，饱和脂肪酸的含量可以忽略不计，单烯脂肪酸含量降低很多；高吸附能力的柱层析是提取PUFA单体的较好方法，其产物的纯度达98%以上。

Self-assembly of large, ordered lamellae from non-bilayer lipids and integral membrane proteins in vitro

In many biological membranes, the major lipids are “non-bilayer lipids,” which in purified form cannot be arranged in a lamellar structure. The structural and functional roles of these lipids are poorly understood. This work demonstrates that the in vitro association of the two main components of a membrane, the non-bilayer lipid monogalactosyldiacylglycerol (MGDG) and the chlorophyll-a/b light-harvesting antenna protein of photosystem II (LHCII) of pea thylakoids, leads to the formation of large, ordered lamellar structures: (i) thin-section electron microscopy and circular dichroism spectroscopy reveal that the addition of MGDG induces the transformation of isolated, disordered macroaggregates of LHCII into stacked lamellar aggregates with a long-range chiral order of the complexes; (ii) small-angle x-ray scattering discloses that LHCII perturbs the structure of the pure lipid and destroys the inverted hexagonal phase; and (iii) an analysis of electron micrographs of negatively stained 2D crystals indicates that in MGDG-LHCII the complexes are found in an ordered macroarray. It is proposed that, by limiting the space available for MGDG in the macroaggregate, LHCII inhibits formation of the inverted hexagonal phase of lipids; in thylakoids, a spatial limitation is likely to be imposed by the high concentration of membrane-associated proteins.