Department of Physical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza Str. 11/12, 80-233 Gdańsk, Poland.
Institute of Nanotechnology and Materials Science, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza Str. 11/12, 80-233 Gdańsk, Poland.
Int J Mol Sci. 2022 Mar 11;23(6):3027. doi: 10.3390/ijms23063027.
Protein fibrillation leads to formation of amyloids-linear aggregates that are hallmarks of many serious diseases, including Alzheimer's and Parkinson's diseases. In this work, we investigate the fibrillation of a short peptide (K-peptide) from the amyloidogenic core of hen egg white lysozyme in the presence of dimethyl sulfoxide or urea. During the studies, a variety of spectroscopic methods were used: fluorescence spectroscopy and the Thioflavin T assay, circular dichroism, Fourier-transform infrared spectroscopy, optical density measurements, dynamic light scattering and intrinsic fluorescence. Additionally, the presence of amyloids was confirmed by atomic force microscopy. The obtained results show that the K-peptide is highly prone to form fibrillar aggregates. The measurements also confirm the weak impact of dimethyl sulfoxide on peptide fibrillation and distinct influence of urea. We believe that the K-peptide has higher amyloidogenic propensity than the whole protein, i.e., hen egg white lysozyme, most likely due to the lack of the first step of amyloidogenesis-partial unfolding of the native structure. Urea influences the second step of K-peptide amyloidogenesis, i.e., folding into amyloids.
蛋白质的纤维状折叠会导致淀粉样线性聚集，这是许多严重疾病的标志，包括阿尔茨海默病和帕金森病。在这项工作中，我们研究了来自蛋清溶菌酶的淀粉样核心的短肽（K 肽）在二甲基亚砜或尿素存在下的纤维状折叠。在研究过程中，使用了多种光谱方法：荧光光谱和噻唑蓝 T 测定法、圆二色性、傅里叶变换红外光谱、光密度测量、动态光散射和内源荧光。此外，原子力显微镜还证实了淀粉样物质的存在。所得结果表明，K 肽极易形成纤维状聚集物。这些测量结果还证实了二甲基亚砜对肽纤维状折叠的影响较弱，而尿素的影响则较为明显。我们认为，K 肽比完整蛋白质（即蛋清溶菌酶）具有更高的淀粉样形成倾向，这很可能是由于缺乏淀粉样形成的第一步——天然结构的部分展开。尿素影响 K 肽淀粉样形成的第二步，即折叠成淀粉样。
