Hydrogen Sulfide Inhibits Amyloid Formation

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• 作者：Manuel F. Rosario-Alomar ; Tatiana Qui帽ones-Ruiz ; Dmitry Kurouski ; Valentin Sereda ; Eduardo B. Ferreira ; Lorraine De Jes煤s-Kim ; Samuel Hern谩ndez-Rivera ; Dmitri V. Zagorevski ; Juan L贸pez-Garriga ; Igor K. Lednev
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：January 29, 2015
• 年：2015
• 卷：119
• 期：4
• 页码：1265-1274
• 全文大小：407K
• ISSN：1520-5207

文摘

Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer鈥檚, Parkinson鈥檚, Huntington鈥檚, and vascular dementia. The amount of hydrogen sulfide (H₂S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer鈥檚 disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H₂S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical 尾-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H₂S completely inhibits the formation of 尾-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H₂S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550鈥?00 cm^鈥? spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm^鈥? band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H₂S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils.