Effects of dithiothreitol on the amyloid fibrillogenesis of hen egg-white lysozyme

Abstract

At least 25 human proteins can fold abnormally to form pathological deposits that are associated with several degenerative diseases. Despite extensive investigation on amyloid fibrillation, the detailed molecular mechanisms remain rather elusive and there are currently no effective cures for treating these amyloid diseases. The present study examined the effects of dithiothreitol on the fibrillation of hen egg-white lysozyme (HEWL). Our results revealed that the fibrillation of hen lysozyme was significantly inhibited by reduced dithiothreitol (DTT(red)) while oxidized dithiothreitol (DTT(ox)) had no anti-aggregating activity. Effective inhibitory activity against hen lysozyme fibrillation was observed only when DTT(red) was added within 8 days of incubation. Our results showed that the initial addition of DTT(red) interacted with HEWL, leading to a loss in conformational stability. It was concluded from our findings that DTT(red)-induced attenuation of HEWL fibrillation may be associated with disulfide disruption and extensive structural unfolding of HEWL. Our data may contribute to rational design of effective therapeutic strategies for amyloid diseases.

Anti-amyloidogenic and fibril-destabilizing effects of two manganese–salen derivatives against hen egg-white lysozyme aggregation

“…As stated before, ThT interaction with the ␤-pleated sheet-containing amyloid fibrils leads to an enhancement in ThT fluorescence [8,31,36]. As shown in Fig.…”

“…Variation in surface hydrophobicity of HEWL in the presence of EUK-8 and EUK-134 was examined based on the ANS fluorescence emission spectrum following excitation at 380 nm. ANS, as a hydrophobic fluorescent probe, is widely used for documentation of hydrophobic patches on the surface of amyloid aggregates [8]. Interaction of ANS with hydrophobic regions on proteins, leads to augmentation of fluorescence emission and also a blue shift in the emission maximum [8,37].…”

“…In spite of having distinct amino acid sequences and tertiary structures, these proteins form the same highly ordered amyloid fibrils with common and unique morphological and histochemical properties such as exhibition of cross-␤ structure motif, fibrillar morphology and birefringence upon staining with aromatic dye Congo red [2,[4][5][6][7][8]. Due to these morphological similarities, it has been postulated that different proteins usually follow similar fibril formation pathways.…”

Quantum Calculation of Inelastic Co Collisions With H. I. Rotational Quenching of Low-Lying Rotational Levels

“…At collision energies below ∼10 −3 cm −1 , only s-wave (l = 0) scattering in the incident channel contributes, with the cross section for inelastic collisions varying inversely with the relative velocity, indicative of Wigner's threshold law (Wigner 1948). Similar to that shown in Figure 1, a number of resonances at collision energies between ∼1 and ∼30 cm −1 are evident, but the resonances become suppressed compared with the j = 1 → 0 resonances (see also Yang et al 2006). In general, the cross sections increase with increasing j , with that for j = 0 being the smallest for initial levels j = 3 and 4.…”

Fibril Formation of Bovine α-Lactalbumin Is Inhibited by Glutathione

“…This finding is in line with those revealed from the researches using other reducing agents (e.g., TCEP and DTT) and/or proteins (e.g., hen eggwhite lysozyme). 68,69 A large number of studies have been directed toward seeking or developing potential compounds/molecules to inhibit or prevent amyloid fibrillation and several compounds have been found to retard the formation of fibrils both in vitro and in vivo. 27,28 Similar to other reducing agents such as DTT and cysteine, GSH has been employed by other investigators to disrupt intermolecular disulfide bridges of proteins, protein fragments, and disulfidecontaining surfactant in denaturing conditions.…”