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2015 ; 119
(4
): 1265-74
Nephropedia Template TP
Rosario-Alomar MF
; Quiñones-Ruiz T
; Kurouski D
; Sereda V
; Ferreira EB
; Jesús-Kim LD
; Hernández-Rivera S
; Zagorevski DV
; López-Garriga J
; Lednev IK
J Phys Chem B
2015[Jan]; 119
(4
): 1265-74
PMID25545790
show ga
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 ?-sheet rich fibrils during the course of 70 min at
low pH and high temperatures. The addition of H2S completely inhibits the
formation of ?-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.