Reply to Stradner et al.: Equilibrium clusters are absent in concentrated lysozyme solutions
Reply to Stradner et al.: Equilibrium clusters are absent in concentrated lysozyme solutions
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回复 Stradner 等人：浓溶菌酶溶液中不存在平衡簇
DOI：
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发表时间：
2008
影响因子：
11.1
通讯作者：
D. Svergun
中科院分区：
文献类型：
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作者：
Anuj Shukla;E. Mylonas;E. di Cola;S. Finet;P. Timmins;T. Narayanan;D. Svergun
在他们的文章(1)中，Stradner等人。他说：“令人惊讶的是，峰值位置…基本上与浓度c无关。参考文献中的图1b。1显示了从c=36-273 mg/ml的六个数据集。在我们的文章(2)的正文中，展示了高达c=200 mg/ml的范围内的明显的峰位移，以及支持信息(SI)图。S9(2)对6种浓度(c=20-250 mg/ml)有明显的系统变化。因此，我们不同意文献中所提供的数据之间“没有显著差异”的说法。1和2.在他们的信(3)中，Stradner等人。部分撤销了他们最初的陈述(1)，即“我们都在低浓度时观察到了通常的峰位移动”，并在没有量化这一概念的情况下就集中解决方案进行了辩论。在模拟(4)中观察到的渗流星团对应的较高浓度时，峰移动确实不那么明显，但这种情况与文献[4]中描述的紧凑平衡星团非常不同。1.我们的实验数据没有揭示出平衡团簇的典型小角散射特征。2.相反，数据可以用有物理意义的尺寸和单体的体积分数来很好地描述，这确实允许人们可靠地区分单体和簇合物。相比之下，仅对结构因子(1，4)的模拟是不完整的，因为它们没有考虑预期簇合物的形状因子，而只考虑了单体的形状因子。综上所述，在与文献报道相似的条件下，我们没有观察到浓缩型溶菌酶溶液中平衡团簇的证据。1.在我们的文章(2)中，既没有研究也没有质疑在更高浓度下形成的团簇。
In their article (1), Stradner et al. stated, “Surprisingly, the peak position… is essentially independent” of concentration c referring to figure 1b in ref. 1 displaying six datasets from c = 36–273 mg/ml. In the main text of our article (2) a clear peak shift in the range of up to c = 200 mg/ml was demonstrated, and supporting information (SI) Fig. S9 (2) specifically presented systematic shifts for six concentrations (c = 20–250 mg/ml). We thus disagree with the claim of “no significant differences” between the data presented in refs. 1 and 2. In their letter (3), Stradner et al. partially revoke their original statement (1) to say, “we both observe the usual shift in peak position at low concentrations” and argue about concentrated solutions without quantifying this notion. The peak shift is indeed less pronounced at higher concentrations corresponding to percolating clusters observed in the simulations (4), but this scenario is very different from the compact equilibrium clusters depicted in ref. 1. Our experimental data do not reveal typical small angle scattering features of equilibrium clusters as demonstrated in ref. 2. Instead the data are well described by physically meaningful dimensions and volume fraction of monomers, and this does allow one to reliably distinguish between monomers and clusters. In contrast, simulations of structure factors alone (1, 4) are incomplete because they do not take into account the form factor of the expected clusters but only that of the monomers. Summarizing, we observed no evidence for equilibrium clusters in concentrated lysozyme solutions for conditions similar to those reported in ref. 1. Formation of clusters at yet higher concentrations was neither studied nor questioned in our article (2).