MilliporeSigma

Tau Aggregation Propensity Engrained in Its Solution State.

The journal of physical chemistry. B (2015-10-21)
Neil A Eschmann, Thanh D Do, Nichole E LaPointe, Joan-Emma Shea, Stuart C Feinstein, Michael T Bowers, Songi Han
ABSTRACT

A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, (273)GKVQIINKKLDL(284) (here "R2/WT"), was modified with a spin-label at the N-terminus. With the resulting peptide, R2/G273C-SL, we probed events at time scales spanning seconds to hours after aggregation is initiated using transmission electron microscopy (TEM), thioflavin T (THT) fluorescence, ion mobility mass spectrometry (IMMS), electron paramagnetic resonance (EPR), and Overhauser dynamic nuclear polarization (ODNP) to determine if deliberate changes to its conformational states and population in solution influence downstream propensity to form fibrillar aggregates. We find varying solution conditions by adding the osmolyte urea or TMAO, or simply using different buffers (acetate buffer, phosphate buffer, or water), produces significant differences in early monomer/dimer populations and conformations. Crucially, these characteristics of the peptide in solution state before aggregation is initiated dictate the fibril formation propensity after aggregation. We conclude the driving forces that accelerate aggregation, when heparin is added, do not override the subtle intra- or interprotein interactions induced by the initial solvent conditions. In other words, the balance of protein-protein vs protein-solvent interactions present in the initial solution conditions is a critical driving force for fibril formation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Urea solution, 40 % (w/v) in H2O
Sigma-Aldrich
Glutaraldehyde solution, Grade I, 50% in H2O, specially purified for use as an electron microscopy fixative or other sophisticated use
Sigma-Aldrich
Glutaraldehyde solution, Grade I, 70% in H2O, specially purified for use as an electron microscopy fixative or other sophisticated use
Sigma-Aldrich
Glutaraldehyde solution, Grade I, 25% in H2O, specially purified for use as an electron microscopy fixative
Sigma-Aldrich
Glutaraldehyde solution, Grade II, 25% in H2O
Sigma-Aldrich
Glutaraldehyde solution, 50% in H2O, suitable for photographic applications
Sigma-Aldrich
Glutaraldehyde solution, Grade I, 8% in H2O, specially purified for use as an electron microscopy fixative or other sophisticated use
Sigma-Aldrich
Urea solution, BioUltra, ~8 M in H2O
Sigma-Aldrich
Glutaric dialdehyde solution, 50 wt. % in H2O, FCC
Sigma-Aldrich
Urea-12C, 99.9 atom % 12C
Sigma-Aldrich
Glutaraldehyde solution, 50 wt. % in H2O
Supelco
Urea, 8 M (after reconstitution with 16 mL high purity water)
Sigma-Aldrich
Urea, powder, BioReagent, for molecular biology, suitable for cell culture
Sigma-Aldrich
Urea, ACS reagent, 99.0-100.5%
Sigma-Aldrich
Urea, BioXtra, pH 7.5-9.5 (20 °C, 5 M in H2O)
Sigma-Aldrich
Urea, ReagentPlus®, ≥99.5%, pellets
Sigma-Aldrich
Urea, meets USP testing specifications
Sigma-Aldrich
Urea, suitable for electrophoresis
Sigma-Aldrich
Urea, BioUltra, for molecular biology, 99% (T)
Sigma-Aldrich
Urea, puriss., meets analytical specification of Ph. Eur., BP, USP, 99.0-100.5%, 99.0-101.0% (calc. on dry substance)
Sigma-Aldrich
Urea, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99%