scholarly journals Trehalose Effect on The Aggregation of Model Proteins into Amyloid Fibrils

Life ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 60
Author(s):  
Eleonora Mari ◽  
Caterina Ricci ◽  
Silvia Pieraccini ◽  
Francesco Spinozzi ◽  
Paolo Mariani ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Amyloid Fibrils ◽  
Uv Spectroscopy ◽  
Slowing Down ◽  
Self Assembling ◽  
X Ray Scattering ◽  
Key Factor ◽  
Plausible Mechanism ◽  
Protein Fibrillation ◽  
Reported Data

Protein aggregation into amyloid fibrils is a phenomenon that attracts attention from a wide and composite part of the scientific community. Indeed, the presence of mature fibrils is associated with several neurodegenerative diseases, and in addition these supramolecular aggregates are considered promising self-assembling nanomaterials. In this framework, investigation on the effect of cosolutes on protein propensity to aggregate into fibrils is receiving growing interest, and new insights on this aspect might represent valuable steps towards comprehension of highly complex biological processes. In this work we studied the influence exerted by the osmolyte trehalose on fibrillation of two model proteins, that is, lysozyme and insulin, investigated during concomitant variation of the solution ionic strength due to NaCl. In order to monitor both secondary structures and the overall tridimensional conformations, we have performed UV spectroscopy measurements with Congo Red, Circular Dichroism, and synchrotron Small Angle X-ray Scattering. For both proteins we describe the effect of trehalose in changing the fibrillation pattern and, as main result, we observe that ionic strength in solution is a key factor in determining trehalose efficiency in slowing down or blocking protein fibrillation. Ionic strength reveals to be a competitive element with respect to trehalose, being able to counteract its inhibiting effects toward amyloidogenesis. Reported data highlight the importance of combining studies carried out on cosolutes with valuation of other physiological parameters that may affect the aggregation process. Also, the obtained experimental results allow to hypothesize a plausible mechanism adopted by the osmolyte to preserve protein surface and prevent protein fibrillation.

Quasielastische Lichtstreuung von isoliertem Chromatin / Quasielastic Light Scattering of Isolated Chromatin

1983 ◽  
Vol 38 (1-2) ◽  
pp. 126-134 ◽  
Author(s):  
Bernd Meuel ◽  
Holger Notbohm
Keyword(s):  
Light Scattering ◽  
Ionic Strength ◽  
Structural Changes ◽  
Gel Chromatography ◽  
Quasielastic Light Scattering ◽  
Self Assembling ◽  
X Ray Scattering ◽  
Monovalent Salt ◽  
Quaternary Structures ◽  
Low Ionic Strength

Chromatin undergoes structural changes in dependence on the ionic strength of monovalent cations. At low ionic strength an extended chain of nucleosomes is apparent while with increasing ionic strength more compact structures are formed. Soluble chromatin was prepared from rat liver and fractionated by gel chromatography. Quasielastic light scattering experiments on chromatin were done with monovalent salt concentrations ranging from 3-150 mм. Using this method translational diffusion coefficients have been derived. These appeared to be nearly independent of monovalent salt concentrations, indicating that the hydrodynamic radius of chromatin molecules did not change. On the other hand, sedimentation coefficients were increasing according to an exponential relation. Taken together, both findings reveal a rising of the molar mass with increasing ionic strength. On the contrary, chromatin prepared in physiological salt apparently disintegrates by lowering the ionic strength. Furthermore, it could be demonstrated by earlier small angle X-ray scattering studies that the diameter of the higher order chromatin fiber remained constant at approximately 32 nm even if these structures had been reconstituted from smaller pieces starting at low ionic strength. Thus, isolated chromatin fibers are capable of self-assembling to regular quaternary structures, even if the DNA does not form a continuous strand.

scholarly journals Endo-lysosomal Aβ concentration and pH enable formation of Aβ oligomers that potently induce Tau missorting

2020 ◽  
Author(s):  
Marie P. Schützmann ◽  
Filip Hasecke ◽  
Sarah Bachmann ◽  
Mara Zielinski ◽  
Sebastian Hänsch ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Tau Pathology ◽  
Aβ Oligomers ◽  
Lysosomal Ph ◽  
Amyloid Fibril Formation ◽  
Aβ Amyloid ◽  
Key Factor ◽  
Lysosomal System

AbstractAmyloid-β peptide (Aβ) forms metastable oligomers >50 kD, termed AβOs or protofibrils, that are more effective than Aβ amyloid fibrils at triggering Alzheimer’s disease-related processes such as synaptic dysfunction and Tau pathology, including Tau mislocalization. In neurons, Aβ accumulates in endo-lysosomal vesicles at low pH. Here, we show that the rate of AβO assembly is accelerated 8,000-fold upon pH reduction from extracellular to endo-lysosomal pH, at the expense of amyloid fibril formation. The pH-induced promotion of AβO formation and the high endo-lysosomal Aβ concentration together enable extensive AβO formation of Aβ42 under physiological conditions. Exploiting the enhanced AβO formation of the dimeric Aβ variant dimAβ we furthermore demonstrate targeting of AβOs to dendritic spines, potent induction of Tau missorting, a key factor in tauopathies, and impaired neuronal activity. The results suggest that the endosomal/lysosomal system is a major site for the assembly of pathomechanistically relevant AβOs.

scholarly journals Truncated Prosequence of Rhizopus oryzae Lipase: Key Factor for Production Improvement and Biocatalyst Stability

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 961 ◽  
Author(s):  
Josu López-Fernández ◽  
Juan J. Barrero ◽  
M. Dolors Benaiges ◽  
Francisco Valero
Keyword(s):  
Amino Acids ◽  
Ionic Strength ◽  
Rhizopus Oryzae ◽  
Lipase Production ◽  
Biochemical Properties ◽  
Mature Sequence ◽  
Rhizopus Oryzae Lipase ◽  
Batch Cultures ◽  
Production Improvement ◽  
Key Factor

Recombinant Rhizopus oryzae lipase (mature sequence, rROL) was modified by adding to its N-terminal 28 additional amino acids from the C-terminal of the prosequence (proROL) to obtain a biocatalyst more suitable for the biodiesel industry. Both enzymes were expressed in Pichia pastoris and compared in terms of production bioprocess parameters, biochemical properties, and stability. Growth kinetics, production, and yields were better for proROL harboring strain than rROL one in batch cultures. When different fed-batch strategies were applied, lipase production and volumetric productivity of proROL-strain were always higher (5.4 and 4.4-fold, respectively) in the best case. rROL and proROL enzymatic activity was dependent on ionic strength and peaked in 200 mM Tris-HCl buffer. The optimum temperature and pH for rROL were influenced by ionic strength, but those for proROL were not. The presence of these amino acids altered lipase substrate specificity and increased proROL stability when different temperature, pH, and methanol/ethanol concentrations were employed. The 28 amino acids were found to be preferably removed by proteases, leading to the transformation of proROL into rROL. Nevertheless, the truncated prosequence enhanced Rhizopus oryzae lipase heterologous production and stability, making it more appropriate as industrial biocatalyst.

scholarly journals Guanosine Quadruplexes in Solution: A Small-Angle X-Ray Scattering Analysis of Temperature Effects on Self-Assembling of Deoxyguanosine Monophosphate

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
P. Mariani ◽  
F. Spinozzi ◽  
F. Federiconi ◽  
M. G. Ortore ◽  
H. Amenitsch ◽  
...  
Keyword(s):  
Small Angle ◽  
Temperature Effects ◽  
The Self ◽  
X Ray ◽  
Self Assembling ◽  
X Ray Scattering ◽  
G Quadruplex ◽  
Global Fit ◽  
Quadruplex Formation ◽  
Ray Scattering

We investigated quadruplex formation in aqueous solutions of2′-deoxyriboguanosine5′-monophosphate, d(pG), which takes place in the absence of the covalent axial backbone. A series of in-solution small angle X-ray scattering experiments on d(pG) have been performed as a function of temperature in the absence of excess salt, at a concentration just above the critical one at which self-assembling occurs. A global fit approach has been used to derive composition and size distribution of the scattering particles as a function of temperature. The obtained results give thermodynamical justification for the observed phase-behavior, indicating that octamer formation is essential for quadruplex elongation. Our investigation shows that d(pG) quadruplexes are very suitable to assess the potential of G-quadruplex formation and to study the self-assembling thermodynamics.

scholarly journals pH-induced molecular shedding drives the formation of amyloid fibril-derived oligomers

2015 ◽  
Vol 112 (18) ◽  
pp. 5691-5696 ◽  
Author(s):  
Kevin W. Tipping ◽  
Theodoros K. Karamanos ◽  
Toral Jakhria ◽  
Matthew G. Iadanza ◽  
Sophia C. Goodchild ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Correlation Spectroscopy ◽  
Synthetic Membranes ◽  
Fluorescence Correlation ◽  
Amyloid Toxicity ◽  
Tht Fluorescence ◽  
Amyloid Aggregates ◽  
Key Factor ◽  
Cellular Dysfunction ◽  
Acidic Compartments

Amyloid disorders cause debilitating illnesses through the formation of toxic protein aggregates. The mechanisms of amyloid toxicity and the nature of species responsible for mediating cellular dysfunction remain unclear. Here, using β2-microglobulin (β2m) as a model system, we show that the disruption of membranes by amyloid fibrils is caused by the molecular shedding of membrane-active oligomers in a process that is dependent on pH. Using thioflavin T (ThT) fluorescence, NMR, EM and fluorescence correlation spectroscopy (FCS), we show that fibril disassembly at pH 6.4 results in the formation of nonnative spherical oligomers that disrupt synthetic membranes. By contrast, fibril dissociation at pH 7.4 results in the formation of nontoxic, native monomers. Chemical cross-linking or interaction with hsp70 increases the kinetic stability of fibrils and decreases their capacity to cause membrane disruption and cellular dysfunction. The results demonstrate how pH can modulate the deleterious effects of preformed amyloid aggregates and suggest why endocytic trafficking through acidic compartments may be a key factor in amyloid disease.

scholarly journals Actin oligomers at the initial stage of polymerization induced by increasing temperature at low ionic strength: Study with small-angle X-ray scattering

BIOPHYSICS ◽  
2010 ◽  
Vol 6 ◽  
pp. 1-11 ◽  
Author(s):  
Takaaki Sato ◽  
Togo Shimozawa ◽  
Toshiko Fukasawa ◽  
Masako Ohtaki ◽  
Kenji Aramaki ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Initial Stage ◽  
Increasing Temperature ◽  
Low Ionic Strength ◽  
Ray Scattering

The Numerical Simulation of Moisture Transportation in Unsaturated Concrete of Underwater Tunnel

2013 ◽  
Vol 275-277 ◽  
pp. 1190-1193
Author(s):  
Yuan Zhu Zhang ◽  
Xiao Zhen Li ◽  
Xin Jiang Wei
Keyword(s):  
Water Saturation ◽  
Nonlinear Partial Differential Equation ◽  
Moisture Diffusion ◽  
Tunnel Wall ◽  
Slowing Down ◽  
Key Factor ◽  
Underwater Concrete ◽  
Underwater Tunnel ◽  
Over Time

Moisture transportation is a key factor to affect the long-term safety of underwater concrete tunnel. According to the inside and outside environment of tunnel, the moisture transportation equation in unsaturated concrete of underwater tunnel was raised. Finite difference method was adopted to solve the nonlinear partial differential equation of moisture diffusion. The study shows that the changes of water saturation in concrete are mainly concentrated in the surface of tunnel wall and amplitude is gradually slowing down over time. Saturation changes greater in the outside than inside. The wetting state is more obvious than drying state.

Sign in / Sign up

Export Citation Format

Share Document