芜菁黄花叶病毒的平衡沉降
Equilibrium sedimentation of turnip yellow mosaic virus.
作者信息
McGee J H, Kupke D W, Godschalk W, Beams J W
出版信息
Proc Natl Acad Sci U S A. 1974 Oct;71(10):3866-8. doi: 10.1073/pnas.71.10.3866.
Sedimentation equilibrium was achieved with turnip yellow mosaic virus at low speeds (600 rpm) in a magnetic ultracentrifuge. The experiments were carried out in the newly installed constant-speed rotor, equipped with automatic control and an electromagnetic drive. A particle mass of 5.55 x 10(6) daltons was calculated for the virus at vanishing concentrations, in essential agreement with the earlier results using the more tedious procedure with a freely coasting rotor. In order to interpret the observed departure from ideal behavior (nonassociating conditions), preferential interaction experiments were carried out by magnetic densimetry. These showed that a strong Donnan effect exists at pH 7, which contributed > 10(3) times more to the nonideality than did the excluded volume effect. A net negative charge of about 3.5 x 10(3) per particle was estimated at this pH.
在磁性超速离心机中以低速（600转/分钟）使芜菁黄花叶病毒达到沉降平衡。实验在新安装的恒速转子中进行，该转子配备自动控制和电磁驱动装置。在浓度趋近于零时，计算出病毒的粒子质量为5.55×10⁶道尔顿，这与早期使用更繁琐的自由滑行转子程序得到的结果基本一致。为了解释观察到的偏离理想行为（非缔合条件），通过磁密度法进行了优先相互作用实验。结果表明，在pH 7时存在强烈的唐南效应，其对非理想性的贡献比排斥体积效应大10³倍以上。在此pH值下，估计每个粒子的净负电荷约为3.5×10³。
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