Kostner G M, Oettl K, Jauhiainen M, Ehnholm C, Esterbauer H, Dieplinger H
Institute of Medical Biochemistry, University of Graz, Austria.
Biochem J. 1995 Jan 15;305 ( Pt 2)(Pt 2):659-67. doi: 10.1042/bj3050659.
alpha-Tocopherol (alpha-T), an important anti-oxidant of plasma lipoproteins and cell membranes, is secreted from liver together with very-low-density lipoproteins into the blood stream. Other serum lipoprotein classes gain alpha-T by exchange and transfer processes. We show here that the lipoprotein-free d > 1.22 g/ml fraction of human or pig serum increases the exchange rate of alpha-T by a factor of 2-4 as compared with spontaneous exchange/transfer. The alpha-T exchange/transfer (alpha-TET) activity was purified by multiple-step column chromatography. It gave a single band in PAGE with an apparent molecular mass of 75 kDa, and was found to be identical with the phospholipid transfer protein (PLTP). PLTP catalysed alpha-T exchange between different lipoprotein classes, as well as the transfer of alpha-T from artificial liposomes to high-density lipoproteins. The alpha-TET activity measured with a newly developed assay in ten healthy people was 2.45 +/- 0.88 nmol.ml-1.h-1.alpha-TET activity was negatively correlated with plasma low-density lipoprotein-cholesterol (r = -0.75; P < 0.01). It is concluded that human PLTP catalyses exchange/transfer processes of alpha-T between lipid compartments. This factor may be of relevance in atherogenesis and tumour initiation and growth.
α-生育酚（α-T）是血浆脂蛋白和细胞膜的一种重要抗氧化剂，它与极低密度脂蛋白一起从肝脏分泌进入血流。其他血清脂蛋白类别通过交换和转移过程获得α-T。我们在此表明，与自发交换/转移相比，人或猪血清中脂蛋白-free d > 1.22 g/ml部分可使α-T的交换速率提高2至4倍。α-T交换/转移（α-TET）活性通过多步柱色谱法纯化。它在聚丙烯酰胺凝胶电泳（PAGE）中呈现单一条带，表观分子量为75 kDa，并且被发现与磷脂转运蛋白（PLTP）相同。PLTP催化不同脂蛋白类别之间的α-T交换，以及α-T从人工脂质体向高密度脂蛋白的转移。在十名健康人中用新开发的测定法测得的α-TET活性为2.45 +/- 0.88 nmol.ml-1.h-1。α-TET活性与血浆低密度脂蛋白胆固醇呈负相关（r = -0.75；P < 0.01）。结论是，人PLTP催化脂质区室之间α-T的交换/转移过程。该因素可能与动脉粥样硬化以及肿瘤的起始和生长有关。
