Comparative Fourier transform infrared spectroscopy study of cold-, pressure-, and heat-induced unfolding and aggregation of myoglobin
Comparative Fourier transform infrared spectroscopy study of cold-, pressure-, and heat-induced unfolding and aggregation of myoglobin
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DOI：
10.1016/s0006-3495(02)75605-1
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发表时间：
2002-05-01
影响因子：
3.4
通讯作者：
Heremans, K
中科院分区：
文献类型：
--
作者：
Meersman, F;Smeller, L;Heremans, K
用傅里叶变换红外光谱研究了肌红蛋白的冷去折叠，并与压力和热去折叠进行了比较。由于蛋白质聚集是一种具有医学和生物技术意义的现象，因此我们对各自未折叠状态的结构变化和聚集行为都感兴趣。冷和压力诱导的展开都产生部分展开状态，其特征在于持久量的二级结构，其中G和H螺旋的稳定核心被保留。在这方面，冷-和压力-未折叠状态显示出与肌红蛋白早期折叠中间体的相似性。相反，热展开导致形成典型的分子间反平行β-折叠聚集的红外带。这意味着α-螺旋转化为分子间β-折叠。H/H-2-交换数据表明，螺旋首先展开，然后形成分子间β-折叠。压力和冷展开状态不会产生分子间聚集带，这是许多热展开蛋白质红外光谱的典型特征。这表明冷和压力展开的路径与热展开的路径有很大的不同。回到环境条件后，冷或压力处理的蛋白质采用部分重折叠的构象。它在比天然状态（74 ℃）更低的温度（32 ℃）下聚集。
We studied the cold unfolding of myoglobin with Fourier transform infrared spectroscopy and compared it with pressure and heat unfolding. Because protein aggregation is a phenomenon with medical as well as biotechnological implications, we were interested in both the structural changes as well as the aggregation behavior of the respective unfolded states. The cold- and pressure-induced unfolding both yield a partially unfolded state characterized by a persistent amount of secondary structure, in which a stable core of G and H helices is preserved. In this respect the cold- and pressure-unfolded states show a resemblance with an early folding intermediate of myoglobin. In contrast, the heat unfolding results in the formation of the infrared bands typical of intermolecular antiparallel beta-sheet aggregation. This implies a transformation of alpha-helix into intermolecular beta-sheet. H/H-2-exchange data suggest that the helices are first unfolded and then form intermolecular beta-sheets. The pressure and cold unfolded states do not give rise to the intermolecular aggregation bands that are typical for the infrared spectra of many heat-unfolded proteins. This suggests that the pathways of the cold and pressure unfolding are substantially different from that of the heat unfolding. After return to ambient conditions the cold- or pressure-treated proteins adopt a partially refolded conformation. This aggregates at a lower temperature (32degreesC) than the native state (74degreesC).