LIPID OXIDATION AND GEL TO LIQUID-CRYSTALLINE TRANSITION-TEMPERATURES OF SYNTHETIC POLY-UNSATURATED MIXED-ACID PHOSPHATIDYLCHOLINES
LIPID OXIDATION AND GEL TO LIQUID-CRYSTALLINE TRANSITION-TEMPERATURES OF SYNTHETIC POLY-UNSATURATED MIXED-ACID PHOSPHATIDYLCHOLINES
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DOI：
10.1016/0005-2736(83)90229-8
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
KEOUGH, KMW
中科院分区：
文献类型：
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作者：
COOLBEAR, KP;KEOUGH, KMW
多不饱和磷脂酰胆碱1-硬脂酰基-2-亚油酰基-sn-甘油基-3-磷酸胆碱（SLPC）和1-硬脂酰基-2-α-亚麻酰-sn-甘油基-3-磷酸胆碱（SLnPC）有时在合成和储存过程中发生自氧化。用紫外线照射处理未氧化的SLPC也诱导氧化。通过TLC、脂肪酸和UV光谱分析估计氧化。随着有限的氧化，这些脂质的水分散体的凝胶到液晶的转变温度被认为是增加。广泛的氧化导致转变焓降低。转变温度的增加与共轭双键的存在一致，如在230 nm处的吸收增加所示，并且在氧化脂质中的反式双键导致在双层内产生更刚性的结构域。转变中的一些变化，特别是广泛氧化后焓的降低，可能是由于存在少量溶血磷脂酰胆碱[lysoPC]和薄层分析观察到的其他氧化中间体或分解产物。然而，未氧化的SLPC与氧化样品中发现的lysostearoylPC量的混合物的热谱图显示，lysoPC可能不会显著增加转变温度。薄层分析表明，交联产物的存在可能有助于观察到的热致性。
Synthetic preparations of the polyunsaturated phosphatidylcholines 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (SLPC) and 1-stearoyl-2-.alpha.-linolenoyl-sn-glycero-3-phosphocholine (SLnPC) were observed to undergo autooxidation sometimes during synthesis and also on storage. Oxidation was also induced by treatment of unoxidized SLPC with UV irradiation. Oxidation was estimated by TLC, fatty acid and UV spectral analyses. With limited oxidation, the gel to liquid-crystalline transition temperatures of aqueous dispersions of these lipids were seen to increase. Extensive oxidation led to a reduction in the enthalpies of the transitions. The increases in transition temperatures were consistent with the presence of conjugated double bonds, as shown by increased absorption at 230 nm, and trans double bonds, in the oxidized lipids leading to the creation of more rigid domains within the bilayer. Some of the changes in the transitions, especially the decreasing enthalpy after extensive oxidation, may have occurred because of the presence of small amounts of lysophosphatidylcholine [lysoPC] and other oxidation intermediates or breakdown products seen by thin layer analysis. Thermograms of mixtures of unoxidized SLPC with amounts of lysostearoylPC found in the oxidized samples showed, however, that lysoPC likely did not contribute significantly to the increase in transition temperatures. Thin layer analysis suggested that the presence of cross-linked products could have contributed to the observed thermotropic properties.