Brown E M
Eastern Regional Research Center, Agricultural Research Service, Philadelphia, Pennsylvania 19118.
Poult Sci. 1989 Mar;68(3):399-407. doi: 10.3382/ps.0680399.
Apolipoprotein A-I (apo-A-I), the major protein component of chicken high density lipoprotein (HDL), was isolated by hydrophobic interaction chromatography from the lipoprotein fraction of plasma. The apo-A-I was identified from its amino acid composition and molecular weight (by electrophoresis). The isolated protein contained 15% lipid, in the form of neutral lipids and free fatty acids, as compared with 50% lipid, including phospholipid, in intact HDL. The conformation of the isolated protein, as determined from the circular dichroism spectrum, was essentially that of the protein in intact chicken HDL, and similar to that of human HDL. The addition of phospholipid had little effect on the spectrum of this protein. Total delipidation of the protein by extraction with ethanol-diethyl ether mixtures removed the residual lipid, thereby producing an apoprotein with decreased helical structure. The secondary structure of this apoprotein could be restored by the addition of phospholipid.
载脂蛋白A-I（apo-A-I）是鸡高密度脂蛋白（HDL）的主要蛋白质成分，通过疏水相互作用色谱法从血浆脂蛋白组分中分离得到。根据其氨基酸组成和分子量（通过电泳）对apo-A-I进行了鉴定。与完整HDL中含50%脂质（包括磷脂）相比，分离得到的蛋白质含有15%的脂质，呈中性脂质和游离脂肪酸的形式。根据圆二色光谱测定，分离得到的蛋白质的构象与完整鸡HDL中的蛋白质基本相同，且与人类HDL的构象相似。添加磷脂对该蛋白质的光谱影响很小。用乙醇 - 乙醚混合物萃取使蛋白质完全脱脂，去除了残留脂质，从而产生了螺旋结构减少的载脂蛋白。添加磷脂可恢复该载脂蛋白的二级结构。
