Entrapping intermediates of thermal aggregation in alpha-helical proteins with low concentration of guanidine hydrochloride.
Entrapping intermediates of thermal aggregation in alpha-helical proteins with low concentration of guanidine hydrochloride.
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DOI：
10.1074/jbc.m005374200
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发表时间：
2000-09
期刊：
影响因子：
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通讯作者：
Aichun Dong;T. Randolph;John F. Carpenter
中科院分区：
文献类型：
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作者：
Aichun Dong;T. Randolph;John F. Carpenter
蛋白质的聚集是一个具有严重医学意义和重要经济意义的问题。为了制定防止聚集的策略，必须对蛋白质聚集的机制和途径进行表征(S)。本研究用红外光谱研究了肌红蛋白、细胞色素c和溶菌酶三种α-螺旋蛋白在1.0M盐酸胍(GdnHCl)存在和不存在时的热诱导聚集过程。在没有GdnHCl的情况下，在50℃以上，α螺旋带(约1656 cm(-1))的强度随温度的变化而降低。对于肌红蛋白和细胞色素c，螺旋带的丢失伴随着在1694和1623 cm(-1)处出现两条新带，这表明分子间β-折叠聚集体的形成。对于溶菌酶，表明分子间β-折叠聚集体的条带没有出现任何明显的强度。在1.0mGdnHCl存在下，观察到两个主要的中间态，分别富含3(10)-螺旋(1663 cm(-1))和β转角结构(1667 cm(-1))。这些发现表明，结合使用热和化学变性因素的蛋白质聚集的红外光谱研究可以提供一种填充和表征聚集中间体的方法。
Aggregation of proteins is a problem with serious medical implications and economic importance. To develop strategies for preventing aggregation, the mechanism(s) and pathways by which proteins aggregate must be characterized. In this study, the thermally induced aggregation processes of three alpha-helix proteins (myoglobin, cytochrome c, and lysozyme) in the presence and absence of 1.0 m guanidine hydrochloride (GdnHCl) were investigated by means of infrared spectroscopy. In the absence of GdnHCl, intensities of the alpha-helix bands (approximately 1656 cm(-1)) decrease as a function of temperature at above 50 degrees C. With myoglobin and cytochrome c, the loss of helix bands was accompanied by the appearance of two new bands at 1694 and 1623 cm(-1), indicative of the formation of intermolecular beta-sheet aggregates. For lysozyme, bands indicative of intermolecular beta-sheet aggregates did not appear in any significant intensity. In the presence of 1.0 m GdnHCl, two major intermediate states rich in 3(10)-helix (represented by the band at 1663 cm(-1)) and beta-turn structure (represented by the band at 1667 cm(-1)), respectively, were observed. These findings demonstrated that IR spectroscopic studies of protein aggregation using a combination of thermal and chemical denaturing factors could provide a means to populate and characterize aggregation intermediates.