Davis P J, Fleming B D, Coolbear K P, Keough K M
Biochemistry. 1981 Jun 9;20(12):3633-6. doi: 10.1021/bi00515a051.
The gel to liquid-crystalline phase transition temperatures of dispersions of mixed-acid sn-1,2-lecithins which contain one unsaturated and one saturated fatty acid have been studied by differential scanning calorimetry. The temperature for 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (containing no reversed isomer) was -9.3 degrees C while that for 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (containing 8% of the reversed isomer) was -2.6 degrees C. The temperature for 2-oleoyl-1-stearoyl-sn-glycero-3-phosphocholine (containing 6% of the reversed isomer) was 6.3 degrees C while that for 1-oleoyl-2-stearoyl-sn-glycero-3-phosphocholine (containing 18% of the reversed isomer) was 8.6 degrees C. The differences in transition temperatures for the isomers of a pair containing the same two acids were consistent with those observed for positional isomers of saturated mixed-acid lecithins in that the isomer of the pair which had the longer fatty acid in the sn-1 position had the lower temperature. The phase transition temperatures of pairs of isomers containing palmitate and oleate at the sn-1 and -2 positions were different by at least 6.7 degrees C, while those containing stearate and oleate were different by at least 2.3 degrees C. Differences in the chain lengths of the fatty acids at the two positions of the glycerol appear to predominate over differences in the depths of the double bonds in the bilayer in determining the transition temperatures.
通过差示扫描量热法研究了含有一种不饱和脂肪酸和一种饱和脂肪酸的混合酸sn-1,2-卵磷脂分散体从凝胶态到液晶态的相变温度。1-油酰基-2-棕榈酰基-sn-甘油-3-磷酸胆碱（不含反式异构体）的相变温度为-9.3℃，而2-油酰基-1-棕榈酰基-sn-甘油-3-磷酸胆碱（含8%反式异构体）的相变温度为-2.6℃。2-油酰基-1-硬脂酰基-sn-甘油-3-磷酸胆碱（含6%反式异构体）的相变温度为6.3℃，而1-油酰基-2-硬脂酰基-sn-甘油-3-磷酸胆碱（含18%反式异构体）的相变温度为8.6℃。含有相同两种酸的一对异构体的相变温度差异与饱和混合酸卵磷脂的位置异构体所观察到的差异一致，即sn-1位脂肪酸较长的那一对异构体的相变温度较低。在sn-1和-2位含有棕榈酸酯和油酸酯的异构体对的相变温度相差至少6.7℃，而含有硬脂酸酯和油酸酯的异构体对的相变温度相差至少2.3℃。在决定相变温度方面，甘油两个位置上脂肪酸链长度的差异似乎比双层中双键深度的差异更为重要。
