Reversible lattice repacking illustrates the temperature dependence of macromolecular interactions
Reversible lattice repacking illustrates the temperature dependence of macromolecular interactions
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DOI：
10.1006/jmbi.2001.4891
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发表时间：
2001-08-24
影响因子：
5.6
通讯作者：
Matthews, BW
中科院分区：
文献类型：
--
作者：
Juers, DH;Matthews, BW
在大分子X射线晶体学中已经成为常规的快速冷冻，导致晶体大幅收缩。在大肠杆菌β-半乳糖苷酶的情况下，这种变化是可逆的，并且被证明是由于晶格重排。在冷却时，涉及晶格接触的蛋白质表面的面积增加了50%。分子间的接触有很大的变化，这些变化主要是由长的极性侧链。由于熵的原因，这样的侧链以及表面溶剂分子在室温下往往有点无序，但在冷却时可以形成广泛的氢键网络。低温密度测量表明，至少在某些情况下，低温溶剂的有益效果可能是由于玻璃化的密度增加，这减少了需要从晶体中排出的大量溶剂的体积。β-半乳糖苷酶和其他几种蛋白质的分析表明，分子内和分子间的接触界面可以通过低温冷却扰动，但在后一种情况下，变化往往更显着。分子间相互作用的温度依赖性表明，谨慎可能是必要的，在解释蛋白质-蛋白质和蛋白质-核酸相互作用的基础上低温晶体结构。(C)北京：科学出版社.
Flash-freezing, which has become routine in macromolecular X-ray crystallography, causes the crystal to contract substantially. In the case of Escherichia coli beta -galactosidase the changes are reversible and are shown to be due to lattice repacking. On cooling, the area of the protein surface involved in lattice contacts increases by 50%. There are substantial alterations in intermolecular contacts, these changes being dominated by the long, polar side-chains. For entropic reasons such side-chains, as well as surface solvent molecules, tend to be somewhat disordered at room temperature but can form extensive hydrogen-bonded networks on cooling. Low-temperature density measurements suggest that, at least in some cases, the beneficial effect of cryosolvents may be due to a density increase on vitrification which reduces the volume of bulk solvent that needs to be expelled from the crystal. Analysis of beta -galactosidase and several other proteins suggests that both intramolecular and intermolecular contact interfaces can be perturbed by cryocooling but that the changes tend to be more dramatic in the latter case. The temperature-dependence of the intermolecular interactions suggests that caution may be necessary in interpreting protein-protein and protein-nucleic acid interactions based on low-temperature crystal structures. (C) 2001 Academic Press.