Physics Department, The City College of New York, New York, NY, USA.
Photochem Photobiol. 2012 Mar-Apr;88(2):304-10. doi: 10.1111/j.1751-1097.2011.01051.x. Epub 2011 Dec 30.
The Stokes shift of tryptophan (Trp) fluorescence from layers of the lipid-containing bacteriophage φ6 is compared to determine the relative effect of the layers on virus hydrophobicity. In the inner most layer, the empty procapsid (PC) which contains 80-90% of the virion Trp residues, λ(max) = 339.8 nm. The PC emission is substantially more redshifted than the other φ6 layers and nearer to that of the Pseudomonad host cell than the other φ6 layers. The Trp emission from the nucleocapsid (NC) with λ(max) = 337.4 nm, is blueshifted by 2.4 nm relative to the PC although the number of Trp in the NC is identical to the PC. This shift represents an increase in Trp hydrophobicity, likely a requirement for the maintenance of A-form doubled-stranded RNA. Fluorescence from the completely assembled virion indicates it is in a considerably more hydrophobic environment with λ(max) = 330.9 nm. Density measurements show that the water content in the NC does not change during envelope assembly, therefore the blueshifted φ6 emission suggests that the envelope changes the PC environment, probably via the P8 layer. This change in hydrophobicity likely arises from charge redistribution or envelope-induced structural changes in the PC proteins.
比较了含脂噬菌体 φ6 各层色氨酸（Trp）荧光的斯托克斯位移，以确定各层对病毒疏水性的相对影响。在最内层，空衣壳（PC）含有 80-90%的病毒衣壳 Trp 残基，λ(max) = 339.8nm。PC 发射的红移程度明显大于其他 φ6 层，且更接近假单胞菌宿主细胞的发射，而不是其他 φ6 层。尽管 NC 中的 Trp 数量与 PC 相同，但核衣壳（NC）的 Trp 发射λ(max) = 337.4nm，蓝移了 2.4nm。这种位移代表了 Trp 疏水性的增加，可能是维持 A 型双链 RNA 所必需的。完全组装的病毒粒子的荧光表明，它处于更疏水的环境中，λ(max) = 330.9nm。密度测量表明，在包膜组装过程中 NC 中的含水量没有变化，因此 φ6 发射的蓝移表明包膜改变了 PC 环境，可能是通过 P8 层。这种疏水性的变化可能源于电荷再分布或包膜诱导的 PC 蛋白结构变化。
