Bonnefont D, Legrand A, Peynet J, Emerit J, Delattre J, Galli A
Laboratoire de Biochimie, Hôpital de la Salpêtrière, Paris, France.
Clin Chem. 1989 Oct;35(10):2054-8.
We assessed the distribution of malondialdehyde (MDA) in lipoproteins and proteins in serum after using two procedures to separate the lipoproteins: sequential ultracentrifugation or selective precipitation with a sodium phosphotungstate and magnesium chloride reagent followed by ultracentrifugation of the supernate. MDA concentrations were determined by the thiobarbituric acid reaction and quantified by fluorometry. We found that 43% of the thiobarbituric acid-reactive substances (TBARS) was bound to the lipoproteins--27% to very-low- and low-density lipoproteins (VLDL-LDL) and 16% to high-density lipoproteins (HDL)--and from 11.5% to 15.8% to proteins, depending on the separation procedure. Residual unbound TBARS were located in the ultracentrifugation layers that contained no lipoproteins or proteins. The TBARS concentration in serum lipoproteins containing apolipoprotein B (i.e., VLDL-LDL) was the same after ultracentrifugation or selective precipitation. We therefore consider the precipitation method more suitable for routine TBARS determination in these lipoproteins, because it is easier to handle and faster. However, for determination of TBARS in HDL, selective precipitation requires subsequent ultracentrifugation at a density of 1.21 kg/L.
我们采用两种方法分离脂蛋白后，评估了血清中脂蛋白和蛋白质中丙二醛（MDA）的分布：连续超速离心法，或用磷钨酸钠和氯化镁试剂进行选择性沉淀，然后对上清液进行超速离心。通过硫代巴比妥酸反应测定MDA浓度，并通过荧光法进行定量。我们发现，43%的硫代巴比妥酸反应性物质（TBARS）与脂蛋白结合——27%与极低密度脂蛋白和低密度脂蛋白（VLDL-LDL）结合，16%与高密度脂蛋白（HDL）结合——根据分离方法的不同，与蛋白质结合的比例在11.5%至15.8%之间。未结合的残留TBARS位于不含脂蛋白或蛋白质的超速离心层中。超速离心或选择性沉淀后，含载脂蛋白B的血清脂蛋白（即VLDL-LDL）中的TBARS浓度相同。因此，我们认为沉淀法更适合于这些脂蛋白中TBARS的常规测定，因为它操作更简便、速度更快。然而，对于HDL中TBARS的测定，选择性沉淀需要随后在密度为1.21 kg/L下进行超速离心。
