Jarosław Wawer

Inhibition of amyloid fibril formation of hen egg white lysozyme by trimethylamine N-oxide at low pH

In vitro inhibition of the formation of fibrous aggregates of proteins (amyloids) has gained increasing attention due to the number of diseases associated with protein misfolding and fibrillation. An interesting group of compounds for which pronounced activity against this phenomenon can be expected consists of low molecular weight substances (osmolytes) which have the ability to change protein stability. Here we investigate the influence of trimethylamine N-oxide (TMAO) in acidic solution (pH=2) on the fibrillation of hen egg white lysozyme (HEWL). The process was monitored by five techniques: circular dichroism in the UV region, atomic force microscopy, dynamic light scattering, densimetry and gel electrophoresis. The obtained results show that protonated TMAO in a concentration of 400 mM inhibits amyloidogenesis. In the conditions of the experiment the HEWL molecules form clusters about 30 nm in diameter containing a relatively high fraction of covalent-bonded dimers.

Influence of the ionic strength on the amyloid fibrillogenesis of hen egg white lysozyme

The study investigates the role of the electrostatic interactions in the fibrillation of the hen egg white lysozyme (HEWL). In order to achieve this aim the influence of the cations Na+, Mg2+ and Al3+ on the amyloid fibril formation and amorphous aggregation was tested. The amyloids are formed in the solution without added salt but the Thioflavin T fluorescence gives the false-negative result. In these conditions, the HEWL fibrils are long and curvy. If the ionic strength of the solution is sufficiently high, the formed amyloids are shorter and fragmented. Our study shows that the addition of the aluminium salt promotes protein fibrillation. The amorphous aggregation dominates in the high concentration of electrolyte. The in vitro amyloid fibril formation seems to be regulated by universal mechanisms. The theories implemented in the polymer science or for colloidal solutions give the qualitative description of the aggregation phenomena. However, the specific interactions and the additional effects (e.g. fibril fragmentation) modulate the amyloidogenesis.