Shahrokh Z, Nichols A V
Biochim Biophys Acta. 1986 Sep 12;878(2):152-8. doi: 10.1016/0005-2760(86)90141-4.
The effect of plasma components on the particle size distribution and chemical composition of human plasma low-density lipoproteins (LDL) during interaction with discoidal complexes of human apolipoprotein A-I and phosphatidylcholine (PC) was investigated. Incubation (37 degrees C, 1 h and 6 h) of LDL with discoidal complexes in the presence of the plasma ultracentrifugal d greater than 1.20 g/ml fraction (activity of lecithin-cholesterol acyltransferase inhibited) produces an increase in LDL apparent particle diameter two-to six-fold greater than that observed in the absence of the plasma d greater than 1.20 g/ml fraction. In incubation mixtures of LDL and discoidal complexes, both in the presence and absence of the plasma d greater than 1.20 g/ml fraction, the extent of LDL apparent particle diameter increase is: (1) approximately three-fold greater at 6 h than at 1 h, and (2) markedly greater for LDL with initially small (22.4-24.0 nm) major components than for LDL with initially large (26.2-26.8 nm) major components. The facilitation factor in the plasma d greater than 1.20 g/ml fraction is not plasma phospholipid transfer protein. Purified human serum albumin produces an apparent particle diameter increase comparable to the plasma d greater than 1.20 g/ml fraction. The discoidal complex-induced increase in LDL apparent particle diameter value by albumin is associated with an increase in phospholipid uptake by LDL and a decreased loss of LDL unesterified cholesterol. In preliminary experiments, high-density lipoproteins (HDL) reverse the apparent particle diameter increase originally induced by discoidal complexes. The presence of HDL (HDL phospholipid/LDL phospholipid molar ratio of 10:1) in the incubation (6 h) mixture of LDL and discoidal complexes also attenuates LDL apparent particle diameter increase. In vivo, the plasma LDL/HDL ratio may be a controlling factor in determining the extent to which phospholipid uptake and the associated change in LDL particle size distribution occurs.
研究了血浆成分在与人载脂蛋白A-I和磷脂酰胆碱（PC）的盘状复合物相互作用期间对人血浆低密度脂蛋白（LDL）粒径分布和化学成分的影响。在血浆超速离心d大于1.20 g/ml组分存在的情况下（卵磷脂胆固醇酰基转移酶活性受到抑制），将LDL与盘状复合物一起孵育（37℃，1小时和6小时），LDL的表观粒径增加幅度比在没有血浆d大于1.20 g/ml组分的情况下观察到的增加幅度大两到六倍。在LDL和盘状复合物的孵育混合物中，无论是否存在血浆d大于1.20 g/ml组分，LDL表观粒径增加的程度为：（1）6小时时比1小时时大约大三倍；（2）对于最初主要成分粒径小（22.4 - 24.0 nm）的LDL，其增加幅度明显大于最初主要成分粒径大（26.2 - 26.8 nm）的LDL。血浆d大于1.20 g/ml组分中的促进因子不是血浆磷脂转运蛋白。纯化的人血清白蛋白产生的表观粒径增加与血浆d大于1.20 g/ml组分相当。白蛋白引起的盘状复合物诱导的LDL表观粒径值增加与LDL对磷脂摄取的增加以及LDL未酯化胆固醇损失的减少有关。在初步实验中，高密度脂蛋白（HDL）可逆转最初由盘状复合物诱导的表观粒径增加。在LDL和盘状复合物的孵育（6小时）混合物中存在HDL（HDL磷脂/LDL磷脂摩尔比为10:1）也会减弱LDL表观粒径的增加。在体内，血浆LDL/HDL比值可能是决定磷脂摄取程度以及LDL粒径分布相关变化的控制因素。
