LIPOPROTEIN CHARACTERIZING OBSTRUCTIVE JAUNDICE .2. ISOLATION AND PARTIAL CHARACTERIZATION OF PROTEIN MOIETIES OF LOW DENSITY LIPOPROTEINS
LIPOPROTEIN CHARACTERIZING OBSTRUCTIVE JAUNDICE .2. ISOLATION AND PARTIAL CHARACTERIZATION OF PROTEIN MOIETIES OF LOW DENSITY LIPOPROTEINS
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DOI：
10.1172/jci106459
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发表时间：
1970-01-01
影响因子：
15.9
通讯作者：
MCCONATHY, WJ
中科院分区：
文献类型：
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作者：
SEIDEL, D;ALAUPOVIC, P;MCCONATHY, WJ
胆道梗阻时血浆低密度脂蛋白（LDL）的特征几乎完全在于存在免疫化学上不同的脂蛋白家族，脂蛋白B（LP-B B）和脂蛋白X（LP-X）。我们从阻塞性黄疸患者血浆中分离出LP-X和LP-B，并将其与LDL的脂质组成进行比较，结果表明，LP-X是导致LDL脂质组成异常和阻塞性黄疸患者血浆脂质组成异常的主要原因。采用结合超离心、肝素沉淀和乙醇分级的分离程序。而LP-B的特征在于存在载脂蛋白B（Apo B），完整的LP-X含有独特组成的蛋白质部分，由白蛋白（约40%）和特定载脂蛋白Apox（60%）的混合物组成。这两种蛋白质部分通过制备性超离心分离，分离浓度为1.21 μ g/ml的部分去脂LP-X溶液。因此，LP-X包含白蛋白-脂蛋白复合物，其中白蛋白的掩蔽抗原位点可以通过部分或全部脱脂来显示。载脂蛋白X是完整或部分脱脂的LP-X的特征性非白蛋白部分，其免疫化学性质不同于ApoA、ApoB、白蛋白、γ-球蛋白和其他血清蛋白。超电泳、免疫化学和电泳分析结果表明，Apox可能是由几种不同的多肽组成的复杂蛋白。Apox的特征在于其氨基酸组成，以及丝氨酸和苏氨酸作为主要的N-末端和丙氨酸作为主要的C-末端氨基酸。有人认为，载脂蛋白X与载脂蛋白C相似，如果不是相同的话。
The plasma low density lipoproteins (LDL) in biliary obstruction are characterized almost exclusively by the presence of the immunochemically distinct lipoprotein families, lipoprotein B (LP-B) and lipoprotein X (LP-X). It is suggested that LP-X, with its uniquely high content of unesterified cholesterol and phospholipid, is primarily responsible for the unusual lipid composition of LDL and the abnormal plasma lipid composition in obstructive jaundice.To show their protein moieties, we isolated LP-X and LP-B from the LDL in plasma obtained from patients with obstructive jaundice. A separation procedure was employed which combines ultracentrifugation, heparin precipitation, and ethanol fractionation. Whereas LP-B was characterized by the presence of apolipoprotein B (ApoB), intact LP-X contained a protein moiety of unique composition consisting of a mixture of albumin (approximately 40%) and the specific apolipoprotein, ApoX (60%). These two protein moieties were separated by preparative ultracentrifugation at d 1.21 g/ml of a solution of partially delipidized LP-X. LP-X thus comprises an albumin-lipoprotein complex in which the masked antigenic site of albumin can be revealed by partial or total delipidization.Apolipoprotein X, the characteristic nonalbumin protein moiety of intact or partially delipidized LP-X, was immunochemically different from ApoA, ApoB, albumin, γ-globulins, and other serum proteins. The results of analytical ultracentrifugation and the immunochemical and electrophoretic properties of ApoX indicated it to be a complex protein consisting possibly of several nonidentical polypeptides. ApoX was characterized by its amino acid composition, and by serine and threonine as the major N-terminal and alanine as the major C-terminal amino acids. It has been suggested that ApoX is similar to, if not identical with, apolipoprotein C.Images