Durham A C, Witz J, Bancroft J B
Institut de Biologie Moleculaire et Cellulaire du C.N.R.S., 15 rue Descartes, 67084 Strasbourg Cedex, France.
Virology. 1984 Feb;133(1):1-8. doi: 10.1016/0042-6822(84)90419-7.
Hydrogen-ion titration curves are reported for tomato bushy stunt virus, two strains of cowpea chlorotic mottle virus, and turnip crinkle virus, with particular attention to the hysteresis loops associated with the swelling and contraction of virions. There appears to be an archetypal shape of hysteresis loops, which is shared by viruses in several groups, suggestive of many intermediate states in the swelling of any one particle. In contrast, eggplant mosaic virus behaves as if its protein capsid is impermeable to small ions in mild conditions; its cation-binding sites were revealed by treatment with high concentrations of salt or urea, or at raised temperatures. Putting these observations together with the fact that a spherical virus capsid is a closed, holey, charged surface leads to a theory of titration hysteresis: its key feature is that the protein capsids of simple viruses are inherently semipermeable, with many of the ion-handling properties usually attributed only to complex lipid membranes.
本文报道了番茄丛矮病毒、两种豇豆褪绿斑驳病毒株系以及芜菁皱缩病毒的氢离子滴定曲线，特别关注了与病毒粒子肿胀和收缩相关的滞后环。滞后环似乎有一种原型形状，几个病毒组中的病毒都有这种形状，这表明任何一个粒子在肿胀过程中存在许多中间状态。相比之下，茄子花叶病毒在温和条件下其蛋白质衣壳似乎对小离子不可渗透；通过用高浓度盐或尿素处理或在升高的温度下处理，揭示了其阳离子结合位点。将这些观察结果与球形病毒衣壳是一个封闭、有孔、带电表面这一事实结合起来，得出了滴定滞后理论：其关键特征是简单病毒的蛋白质衣壳本质上是半透性的，具有许多通常仅归因于复杂脂质膜的离子处理特性。
