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Amyloid beta-protein: monomer structure and early aggregation states of Abeta42 and its Pro19 alloform

Summer L Bernstein1, Thomas Wyttenbach, Andrij Baumketner

  • 1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9501, USA.

Journal of the American Chemical Society
|February 17, 2005
PubMed

Insights

Soluble amyloid beta-protein (Abeta) oligomers are implicated in Alzheimer's disease (AD). This study used mass spectrometry to analyze Abeta42 and its Pro19 variant, revealing distinct aggregation pathways and oligomeric species relevant to AD pathogenesis.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Analytical Chemistry

Background:

  • Alzheimer's disease (AD) is a neurodegenerative disorder linked to amyloid beta-protein (Abeta) accumulation.
  • Soluble Abeta oligomers are considered the primary neurotoxic species in AD pathogenesis.
  • Abeta42 is strongly associated with AD, despite lower production levels compared to Abeta40.

Purpose of the Study:

  • To investigate the aggregation behavior and structural characteristics of Abeta42 and its Pro19 alloform.
  • To elucidate the role of specific amino acid substitutions in Abeta aggregation.
  • To characterize oligomeric species formed by Abeta42 and its variants using advanced analytical techniques.

Main Methods:

  • Application of mass spectrometry (MS) and ion mobility (IM) techniques.
  • Characterization of electrosprayed, solution-like monomeric structures of Abeta.
  • Analysis of Abeta solutions before and after filtration to identify different oligomeric states.

Main Results:

  • The Phe19 --> Pro19 substitution in Abeta42 inhibits fibril formation.
  • [Pro19]Abeta42 solutions predominantly form monomers, dimers, trimers, and tetramers, lacking large oligomers.
  • Filtered Abeta42 solutions yield monomers, dimers, tetramers, hexamers, and a dimer of hexamers, suggesting early protofibril formation.

Conclusions:

  • The study provides insights into the aggregation mechanisms of Abeta peptides.
  • Oligomeric species distribution is dependent on peptide sequence and solution conditions.
  • Findings support proposed aggregation models and highlight the importance of specific Abeta forms in AD.

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