Structural and energetic consequences of disruptive mutations in a protein core.
Structural and energetic consequences of disruptive mutations in a protein core.
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DOI：
10.1021/bi00132a025
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发表时间：
1992-05
期刊：
影响因子：
2.9
通讯作者：
W. Lim;D. Farruggio;R. Sauer
中科院分区：
文献类型：
--
作者：
W. Lim;D. Farruggio;R. Sauer
我们已经表征了一组λ阻遏物的N-末端结构域的变体在疏水核心中具有破坏性突变的性质。这些突变包括一些显著改变总核心残基体积（通过多达六个亚甲基）的突变和一些将单个极性残基置于另外的疏水核心中的突变。纯化的蛋白质的结构特性进行了研究，通过CD光谱，生物活性，识别构象特异性单克隆抗体，和1H NMR光谱。通过热变性和盐酸胍变性测定了蛋白质的稳定性。具有破坏性核心突变的蛋白质被发现显示出连续不断的非天然性质。大的内部体积变化导致显着的构象重排和不稳定高达5千卡/摩尔。在核心位置具有极性取代的变体不再表现得像折叠良好的蛋白质，而是显示出熔融球的特征。然而，即使是带有一些最具破坏性突变的蛋白质也保留了野生型蛋白质的许多原始二级和三级结构特征。这些结果表明，原生结构的原始元素可以在没有正常核心包装的情况下形成。
We have characterized the properties of a set of variants of the N-terminal domain of lambda repressor bearing disruptive mutations in the hydrophobic core. These mutations include some that dramatically alter the total core residue volume (by up to six methylene groups) and some that place a single polar residue into the otherwise hydrophobic core. The structural properties of the purified proteins have been studied by CD spectroscopy, biological activity, recognition by conformation-specific monoclonal antibodies, and 1H NMR spectroscopy. The stabilities of the proteins have been measured by thermal and guanidine hydrochloride denaturation. Proteins with disruptive core mutations are found to display a continuum of increasingly nonnative properties. Large internal volume changes cause both significant conformational rearrangements and destabilization by up to 5 kcal/mol. Variants with polar substitutions at core positions no longer behave like well-folded proteins but rather display characteristics of molten globules. However, even proteins bearing some of the most disruptive mutations retain many of the crude secondary and tertiary structural features of the wild-type protein. These results indicate that primitive elements of native structure can form in the absence of normal core packing.