Correlation between thermal aggregation and stability of lysozyme with salts described by molar surface tension increment: An exceptional propensity of ammonium salts as aggregation suppressor
Correlation between thermal aggregation and stability of lysozyme with salts described by molar surface tension increment: An exceptional propensity of ammonium salts as aggregation suppressor
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DOI：
10.1007/s10930-007-9082-3
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发表时间：
2007-09-01
期刊：
影响因子：
3
通讯作者：
Shiraki, Kentaro
中科院分区：
文献类型：
--
作者：
Hirano, Atsushi;Hamada, Hiroyuki;Shiraki, Kentaro
蛋白质聚集是生物技术和制药工业的关键问题。尽管可溶性蛋白质已被用于许多应用中，但我们对溶液化学对蛋白质聚集的影响的理解仍有待阐明。本文研究了溶菌酶在不同类型盐存在下的热聚集过程。简单的定律被发现了;溶菌酶的聚集速率随着蛋白质的熔融温度（Tm）的增加而增加，这取决于附加盐的化学特性。铵盐，但是，排除了在铵盐的存在下的溶菌酶的聚集率小于从T-M估计。与钠盐相比，铵盐增加了疏水氨基酸的溶解度，说明铵盐吸附了蛋白质的疏水区域，比钠盐更有效地降低了蛋白质的聚集。聚集速率与T-m之间的正相关关系由另一个因素如盐溶液的表面张力来描述。傅立叶变换红外光谱分析表明，热聚集体在高摩尔表面张力增量的溶液中很可能形成β-折叠。这些结果表明，蛋白质聚集归因于溶液的表面自由能。
Protein aggregation is a critical problem for biotechnology and pharmaceutical industries. Despite the fact that soluble proteins have been used for many applications, our understanding of the effect of the solution chemistry on protein aggregation still remains to be elucidated. This paper investigates the process of thermal aggregation of lysozyme in the presence of various types of salts. The simple law was found; the aggregation rate of lysozyme increased with increasing melting temperature of the protein (T-m) governed by chemical characteristics of additional salts. Ammonium salts were, however, ruled out; the aggregation rates of lysozyme in the presence of the ammonium salts were smaller than the ones estimated from T-m. Comparing with sodium salts, ammonium salts increased the solubility of the hydrophobic amino acids, indicating that ammonium salts adsorb the hydrophobic region of proteins, which leads to the decrease in aggregation more effectively than sodium salts. The positive relation between aggregation rate and T-m was described by another factor such as the surface tension of salt solutions. Fourier transform infrared spectral analysis showed that the thermal aggregates were likely to form beta-sheet in solutions that give high molar surface tension increment. These results suggest that protein aggregation is attributed to the surface free energy of the solution.