Zechner R, Dieplinger H, Roscher A, Kostner G M
Biochem J. 1984 Dec 1;224(2):569-76. doi: 10.1042/bj2240569.
Normal fasting human plasma was incubated for 24 h at 37 degrees C in the presence or absence of lecithin:cholesterol acyltransferase (LCAT) inhibitors. The low-density lipoprotein (LDL) fractions of incubated plasma (control LDL and LCAT-modified LDL) were studied with respect to their chemical and functional properties. LCAT-modified LDL differed from control LDL by a decreased phospholipid and free-cholesterol content, but increased cholesteryl esters. Furthermore, an increase of the relative protein content in LDL by 16-20% was found. Apolipoproteins of LCAT-modified LDL exhibited a 10-fold increase of apo AI, a 4-5-fold increase of apo E, and a 2-fold increase of apo C. All these apolipoproteins resided together with apo B on the same particles. LCAT-modified LDL displayed a higher electrophoretic mobility, a higher hydrated density, a decreased flotation constant and a smaller diameter. Cultured human fibroblasts bound and internalized LCAT-modified LDL to a lower extent than control LDL. The degradation, however, was faster. Modified LDL suppressed 3-hydroxy-3-methylglutaryl-CoA reductase activity to a lower extent than did control LDL. Our results demonstrate that LCAT action, together with lipid transfer and exchange processes, markedly alters the chemical and physiochemical properties of LDL. This in turn significantly influences LDL catabolism in vitro.
将正常空腹的人血浆在37℃下于有无卵磷脂胆固醇酰基转移酶（LCAT）抑制剂的情况下孵育24小时。对孵育血浆的低密度脂蛋白（LDL）组分（对照LDL和LCAT修饰的LDL）的化学和功能特性进行了研究。LCAT修饰的LDL与对照LDL的不同之处在于磷脂和游离胆固醇含量降低，但胆固醇酯增加。此外，发现LDL中的相对蛋白质含量增加了16 - 20%。LCAT修饰的LDL的载脂蛋白显示apo AI增加了10倍，apo E增加了4 - 5倍，apo C增加了2倍。所有这些载脂蛋白与apo B一起存在于相同的颗粒上。LCAT修饰的LDL表现出更高的电泳迁移率、更高的水合密度、降低的漂浮常数和更小的直径。培养的人成纤维细胞对LCAT修饰的LDL的结合和内化程度低于对照LDL。然而，其降解更快。修饰的LDL对3 - 羟基 - 3 - 甲基戊二酰辅酶A还原酶活性的抑制程度低于对照LDL。我们的结果表明，LCAT的作用与脂质转移和交换过程一起，显著改变了LDL的化学和物理化学性质。这反过来又在体外显著影响LDL的分解代谢。
