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In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein
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Detection of D-aspartate in tau proteins associated with Alzheimer paired helical filaments

A Kenessey1, S H Yen, W K Liu

  • 1Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Brain Research
|March 27, 1995
PubMed

Insights

Paired helical filaments-tau (PHF-tau) in Alzheimer's disease show increased D-aspartate levels compared to normal tau. This suggests a potential link between tau racemization and neurofibrillary tangle formation.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Alzheimer's Disease Research

Background:

  • Paired helical filaments (PHF) in Alzheimer's disease neurofibrillary lesions contain modified tau proteins (PHF-tau).
  • PHF-tau differs from normal tau (N-tau) in phosphorylation extent and site.
  • Alzheimer's-associated tau (A-tau) and fetal tau (F-tau) also exist for comparison.

Purpose of the Study:

  • To investigate differences in racemization, specifically D-aspartate content, among PHF-tau, N-tau, A-tau, and F-tau.
  • To determine if increased D-aspartate is linked to PHF formation in Alzheimer's disease.

Main Methods:

  • Quantification of D-aspartate content in isolated tau protein fractions.
  • Comparison of D-aspartate percentages across different tau types (PHF-tau, N-tau, A-tau, F-tau).

Main Results:

  • PHF-tau exhibited significantly higher D-aspartate content (4.9%) compared to N-tau (2.8%), A-tau (1.6%), and F-tau (1%).
  • Background correction was applied for accurate D-aspartate percentage determination.

Conclusions:

  • Alzheimer's disease PHF-tau shows elevated levels of D-aspartate, indicating increased protein racemization.
  • The relationship between increased D-aspartate, PHF formation, and tau phosphorylation requires further investigation.

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