Noble R C, Crouchman M L, Moore J H
Lipids. 1975 Dec;10(12):790-9. doi: 10.1007/BF02532322.
A study was made with sheep on the formation in vitro of long chain fatty acid esters of cholesterol by the lecithin-cholesterol-acyltransferase system present in the plasma and the acyl CoA-cholesterola cyltransferase system present in the liver. The rate of cholesterol esterification in the plasma was 0.024 mumoles/ml/hr. The relative pattern of fatty acids esterified during incubation of the plasma remained constant over the 8 hr period of incubation and was similar to the fatty acids in the plasma cholesteryl esters before incubation began and to the fatty acids in the 2-position of the plasma lecithin. The predominant cholesteryl esters synthesized contained monoenoic and dienoic fatty acids. Unlike the bovine, there was no apparent discrimination in favor of the 18:2 containing species of plasma lecithin as donors of fatty acids. This difference could be accounted for by the similarity in the 18:2 content of the phospholipids present in the high density (density greater than 1.062 and less than 1.21) and the low density (density greater than 1.006 and less than 1.063) lipoprotein fractions of the sheep plasma. The possibility of some discrimination against 20:4 during cholesterol ester synthesis in the plasma of the sheep cannot be excluded. In the liver, the predominant cholesteryl esters synthesized contained saturated and monoenoic fatty acids; cholesteryl linoleate was synthesized to a very much less extent. There was considerable similarity between the composition of the unesterified fatty acid fraction of the liver before incubation began and the fatty acid composition of the cholesteryl esters synthesized during incubation. Addition of sonicated suspensions of free fatty acidsaltered markedly the fatty acid pattern of the cholesteryl esters synthesized by the liver slices. From the evidence presented it is concluded that the cholesteryl esters in sheep plasma are syntheized mainly by the plasma lecithin-cholesterol-acyltransferase system. The results are discussed in relation to cholesterol esterification systems demonstrated in the plasma and liver of monogastric animals.
对绵羊进行了一项研究，以观察血浆中存在的卵磷脂 - 胆固醇 - 酰基转移酶系统和肝脏中存在的酰基辅酶A - 胆固醇酰基转移酶系统在体外形成胆固醇长链脂肪酸酯的情况。血浆中胆固醇酯化的速率为0.024微摩尔/毫升/小时。在8小时的孵育期间，血浆孵育过程中酯化的脂肪酸相对模式保持不变，并且与孵育开始前血浆胆固醇酯中的脂肪酸以及血浆卵磷脂2位上的脂肪酸相似。合成的主要胆固醇酯含有单烯酸和二烯酸。与牛不同，作为脂肪酸供体的血浆卵磷脂中含18:2的种类没有明显的偏好。这种差异可以由绵羊血浆高密度（密度大于1.062且小于1.21）和低密度（密度大于1.006且小于1.063）脂蛋白组分中存在的磷脂18:2含量的相似性来解释。不能排除在绵羊血浆胆固醇合成过程中对20:4存在某种歧视的可能性。在肝脏中，合成的主要胆固醇酯含有饱和脂肪酸和单烯酸；亚油酸胆固醇酯的合成程度要低得多。孵育开始前肝脏未酯化脂肪酸部分的组成与孵育期间合成的胆固醇酯的脂肪酸组成之间有相当大的相似性。添加游离脂肪酸的超声悬浮液会显著改变肝切片合成的胆固醇酯的脂肪酸模式。根据所提供的证据得出结论，绵羊血浆中的胆固醇酯主要由血浆卵磷脂 - 胆固醇 - 酰基转移酶系统合成。结合单胃动物血浆和肝脏中已证明的胆固醇酯化系统对结果进行了讨论。
