Patel Roshani, Clark Austin K, DeStefano Gabriella, DeStefano Isabella, Gogoj Hunter, Gray Erin, Patel Aashka Y, Hauner Joshua T, Caputo Gregory A, Vaden Timothy D
Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, 08028, USA.
Biochem Biophys Rep. 2022 Mar 8;30:101242. doi: 10.1016/j.bbrep.2022.101242. eCollection 2022 Jul.
The thermal unfolding of the copper redox protein azurin was studied in the presence of four different dipeptide-based ionic liquids (ILs) utilizing tetramethylguanidinium as the cation. The four dipeptides have different sequences including the amino acids Ser and Asp: TMG-AspAsp, TMG-SerSer, TMG-SerAsp, and TMG-AspSer. Thermal unfolding curves generated from temperature-dependent fluorescence spectroscopy experiments showed that TMG-AspAsp and TMG-SerSer have minor destabilizing effects on the protein while TMG-AspSer and TMG-SerAsp strongly destabilize azurin. Red-shifted fluorescence signatures in the 25 °C correlate with the observed protein destabilization in the solutions with TMG-AspSer and TMG-SerAsp. These signals could correspond to interactions between the Asp residue in the dipeptide and the azurin Trp residue in the unfolded state. These results, supported by appropriate control experiments, suggest that dipeptide sequence-specific interactions lead to selective protein destabilization and motivate further studies of TMG-dipeptide ILs.
利用四甲基胍作为阳离子，在四种不同的基于二肽的离子液体（ILs）存在的情况下，研究了铜氧化还原蛋白天青蛋白的热解折叠。这四种二肽具有不同的序列，包括氨基酸Ser和Asp：TMG-AspAsp、TMG-SerSer、TMG-SerAsp和TMG-AspSer。由温度依赖性荧光光谱实验产生的热解折叠曲线表明，TMG-AspAsp和TMG-SerSer对蛋白质具有轻微的去稳定作用，而TMG-AspSer和TMG-SerAsp则强烈地使天青蛋白去稳定。在25°C时红移的荧光信号与在含有TMG-AspSer和TMG-SerAsp的溶液中观察到的蛋白质去稳定作用相关。这些信号可能对应于二肽中的Asp残基与未折叠状态下的天青蛋白Trp残基之间的相互作用。这些结果在适当的对照实验支持下表明，二肽序列特异性相互作用导致选择性蛋白质去稳定，并推动了对TMG-二肽离子液体的进一步研究。
