Bhattacharya S, Redgrave T G
J Lipid Res. 1981 Jul;22(5):820-8.
The number of particles and the mass of apoprotein B were measured in samples of rat lymph chylomicrons in order to assign the mass of apoprotein B per particle. Chylomicron numbers were estimated by electron microscopy after negative staining with 2% potassium phosphotungstate at pH 4.8. The distribution of particle numbers was plotted against particle volume. An exponential relationship was found. Integration of the function gave an estimate of the total number of particles for the total chylomicron volume, which was calculated from the chemical composition and the partial specific volumes of the constituents. Apoprotein B was measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two procedures were employed to allow for the influence of artefactual flattening of the chylomicrons on the electron microscope grid. First, it was reasoned that the flattening artefact would be greatest for the largest particles, so measurements of subfractions of smaller chylomicrons would be less affected by flattening. The mass of apoprotein B per particle was 0.48 x 10(6) daltons in the smallest subfraction. Second, a correction was applied such that the apparent volume of the oblate spheroid produced by flattening was converted to the true volume of the native spherical particle. The flattening artefact increased exponentially with particle size and was an inverse power function of the surface tension. At an assumed value of chylomicron surface tension of 2 mN/m, the apoprotein B per particle was 0.47 x 10(6) daltons.
为了确定每个大鼠淋巴乳糜微粒中载脂蛋白B的质量，对大鼠淋巴乳糜微粒样本中的微粒数量和载脂蛋白B的质量进行了测量。用2%的磷钨酸钾在pH 4.8条件下进行负染色后，通过电子显微镜估计乳糜微粒数量。将微粒数量的分布与微粒体积作图。发现了一种指数关系。对该函数进行积分得到了总乳糜微粒体积中微粒总数的估计值，该总乳糜微粒体积是根据化学成分和成分的偏比容计算得出的。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测量载脂蛋白B。采用了两种方法来考虑乳糜微粒在电子显微镜网格上人为扁平化的影响。首先，据推断，扁平化假象对最大的微粒影响最大，因此较小乳糜微粒亚组分的测量受扁平化影响较小。最小亚组分中每个微粒的载脂蛋白B质量为0.48×10⁶道尔顿。其次，进行了校正，使得扁平化产生的扁球体的表观体积转换为天然球形微粒的真实体积。扁平化假象随微粒大小呈指数增加，并且是表面张力的反幂函数。在假定的乳糜微粒表面张力为2 mN/m的情况下，每个微粒的载脂蛋白B为0.47×10⁶道尔顿。
