Simultaneous monitoring of peptide aggregate distributions, structure, and kinetics using amide hydrogen exchange: Application to Aβ(1-40) fibrillogenesis

Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, USA.
Biotechnology and Bioengineering (Impact Factor: 4.13). 08/2008; 100(6):1214-1227. DOI: 10.1002/bit.21846


Increasing evidence indicates that soluble aggregates of amyloid beta protein (Abeta) are neurotoxic. However, difficulty in isolating these unstable, dynamic species impedes studies of Abeta and other aggregating peptides and proteins. In this study, hydrogen-deuterium exchange (HX) detected by mass spectrometry (MS) was used to measure Abeta(1-40) aggregate distributions without purification or modification that might alter the aggregate structure or distribution. Different peaks in the mass spectra were assigned to monomer, low molecular weight oligomer, intermediate, and fibril based on HX labeling behavior and complementary assays. After 1 h labeling, the intermediates incorporated approximately ten more deuterons relative to fibrils, indicating a more solvent exposed structure of such intermediates. HX-MS also showed that the intermediate species dissociated much more slowly to monomer than did the very low molecular weight oligomers that were formed at very early times in Abeta aggregation. Atomic force microscopy (AFM) measurements revealed the intermediates were roughly spherical with relatively homogenous diameters of 30-50 nm. Quantitative analysis of the HX mass spectra showed that the amount of intermediate species was correlated with Abeta toxicity patterns reported in a previous study under the same conditions. This study also demonstrates the potential of the HX-MS approach to characterizing complex, multi-component oligomer distributions of aggregating peptides and proteins.

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Available from: Dhara A Patel, Dec 26, 2013
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    • "For example, limited proteolysis, MS, and solution-state NMR spectroscopy were all used together to determine and compare the structure and stability of the Ab21–30 turn within wild-type Ab and seven clinically relevant homologues to highlight the importance of this Ab segment for Ab oligomerization (Grant et al., 2007). Atomic force microscopy (AFM) has also been applied in combination with HDX/MS to study the various aggregated forms of Ab1–40 and provided details that were undetectable by MS such as size and shape of the aggregates (Qi et al., 2008). Analogously, although MALDI-TOF and ESI/MS could be very useful to characterize a newly synthesized decapeptide with an amino acid sequence contained in the full-length Ab, CD, as well as AFM investigations, were necessary to study the influence of the environmental conditions (the presence of metal ions or sodium dodecyl sulfate (SDS)) on the secondary structure of the peptide to confirm a morphological change before and after copper treatment and/or SDS in the surface packing of the peptide shell (Murariu, Dragan, & Drochioiu, 2007). "
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