Freeman R, Leonard K R
J Microsc. 1981 Jun;122(Pt 3):275-86. doi: 10.1111/j.1365-2818.1981.tb01267.x.
A method is described for measuring the mass/length or mass of molecular assemblies by comparative electron scattering in the STEM. Standard particles whose mass is well established (e.g. TMV or fd bacteriophage) are deposited on the electron microscope grid together with the sample to be measured. Images containing at least one sample and standard and with a clean, contamination-free background are chosen and stored on computer disc and then directly integrated. Use of a comparative technique does not require accurate determination of scattering parameters or instrumental geometry and requires only that the limits of linearity be established. The results of the mass/length measurements on phage pf 1, pili, muscle thick filaments and actin are in good agreement with existing molecular weight data and generally have a standard deviation of about 10%. The results for the total mass measurement of the multisubunit enzymes glutamate dehydrogenase and glutamine synthetase are also close to the literature values for their molecular weights. The results for the spherical, Semliki forest and tomato bushy stunt viruses are lower than expected, possibly reflecting some dissociation during preparation.
描述了一种通过扫描透射电子显微镜（STEM）中的比较电子散射来测量分子组装体的质量/长度或质量的方法。将质量已明确的标准颗粒（如烟草花叶病毒或fd噬菌体）与待测样品一起沉积在电子显微镜网格上。选择包含至少一个样品和标准物且背景干净、无污染物的图像，存储在计算机磁盘上，然后直接进行积分。使用比较技术不需要精确测定散射参数或仪器几何形状，只需要确定线性范围。对噬菌体pf 1、菌毛、肌肉粗肌丝和肌动蛋白的质量/长度测量结果与现有的分子量数据高度一致，标准差通常约为10%。对多亚基酶谷氨酸脱氢酶和谷氨酰胺合成酶的总质量测量结果也接近其分子量的文献值。球形的辛德毕斯病毒和番茄丛矮病毒的测量结果低于预期，这可能反映了制备过程中的一些解离现象。
