title: Hydrogen sulfide inhibits amyloid formation.
abstract: Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, and vascular dementia. The amount of hydrogen sulfide (H2S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer's 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 β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of β-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 550-500 cm(-1) spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm(-1) 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.
authors.affiliation: Department of Chemistry and ‡Department of Biology, University of Puerto Rico at Mayagüez , Mayagüez, Puerto Rico 00693.
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Rosario-Alomar
authors.forename: Tatiana
authors.initials: T
authors.lastname: Quiñones-Ruiz
authors.forename: Dmitry
authors.initials: D
authors.lastname: Kurouski
authors.forename: Valentin
authors.initials: V
authors.lastname: Sereda
authors.forename: Eduardo B
authors.initials: EB
authors.lastname: Ferreira
authors.forename: Lorraine De
authors.initials: LD
authors.lastname: Jesús-Kim
authors.forename: Samuel
authors.initials: S
authors.lastname: Hernández-Rivera
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Zagorevski
authors.forename: Juan
authors.initials: J
authors.lastname: López-Garriga
authors.forename: Igor K
authors.initials: IK
authors.lastname: Lednev
mesh_terms: D000682:Amyloid / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D002478:Cells, Cultured; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D018625:Microscopy, Atomic Force; D009113:Muramidase / Q000737:chemistry; D017510:Protein Folding / Q000187:drug effects; D017433:Protein Structure, Secondary
chemical_list: D000682:Amyloid; C421864:hen egg lysozyme; D009113:Muramidase; D006862:Hydrogen Sulfide