Protein stability has been a concern for researchers for a long time as they are sensitive toward their environment. Mostly proteins during experiments require medium that keep them stable at room temperature (RT). Recent research utilizing ionic liquids (ILs) to stabilize protein has gained much importance. Although a few ILs have been claimed to suit this requirement, reported studies employ IL concentrations that might produce irreversible denaturation and aggregation. This study demonstrates the first report for long-term stabilization of horse heart cytochrome c (h-cyt c) by long-chain imidazolium ILs at far low concentration (1 mM) of IL when stored at RT. Long-chain imidazolium ILs until now were less familiar for their stabilizing nature toward protein. A significant increase in the helical content of h-cyt c (dissolved state) was observed with prolonged structural stability (secondary and tertiary) for about 6 months in aqueous solutions of 1-methyl-3-octyl imidazolium chloride [C₈mim][Cl] and 1-decyl-3-methylimidazolium chloride [C₁₀mim][Cl]. The in-depth mechanism discussed suggests interaction of ILs with amino acid residues of h-cyt c, which rigidifies the loop regions with reduced mobility; hence, prolonged stability is achieved. The study firmly advocates the use of long-chain imidazolium ILs as the potent inhibitor against denaturation during storage of h-cyt c at RT.

中文翻译：

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低浓度长链咪唑鎓离子液体赋予细胞色素c长期稳定性的机理和动力学

长期以来，蛋白质稳定性一直是研究人员关注的问题，因为他们对周围环境敏感。在实验过程中，大多数蛋白质都需要能够在室温（RT）下保持稳定的培养基。利用离子液体（IL）稳定蛋白质的最新研究已变得非常重要。尽管已声称一些IL可以满足此要求，但已报道的研究使用的IL浓度可能会导致不可逆的变性和聚集。这项研究证明了马心脏细胞色素c（h-cyt c）是通过长链咪唑类ILs在室温下以极低的IL（1 mM）浓度保存的。迄今为止，长链咪唑类IL对蛋白质的稳定性质尚不为人所知。在1-甲基-3-辛基咪唑鎓氯化物[C ₈ mim]的水溶液中，在大约6个月的时间里，h-cyt c（溶解状态）的螺旋含量显着增加，并且具有较长的结构稳定性（二级和三级）。Cl]和1-癸基-3-甲基咪唑鎓氯化物[C ₁₀ mim] [Cl]。讨论的深入机制表明IL与h-cyt c的氨基酸残基相互作用，从而在降低移动性的情况下加强了循环区域；因此，获得了延长的稳定性。该研究坚决主张使用长链咪唑类ILs作为在h-cyt c于室温下储存期间抗变性的有效抑制剂。