Conformational intermediate of the amyloidogenic protein beta 2-microglobulin at neutral pH

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N H Heegaard1, J W Sen, N C Kaarsholm

  • 1Department of Autoimmunology, Statens Serum Institut, 2300 Copenhagen S, Denmark. nhe@ssi.dk

The Journal of Biological Chemistry
|June 22, 2001
PubMed

Insights

Dialysis-related amyloidosis involves beta(2)-microglobulin fibrillation. This study identifies nonnative protein conformations that may precede amyloid formation, offering insights for detection and inhibition strategies.

Area of Science:

  • Biochemistry
  • Protein Misfolding Diseases
  • Structural Biology

Background:

  • Dialysis-related amyloidosis is characterized by beta(2)-microglobulin (β2M) aggregation and fibrillation.
  • Understanding the early conformational changes in β2M is crucial for elucidating amyloid formation pathways.

Purpose of the Study:

  • To characterize nonnative conformations of beta(2)-microglobulin (β2M) that may precede amyloid fibril formation.
  • To investigate the conditions and properties of these transient protein states.

Main Methods:

  • Capillary electrophoresis to detect and separate protein conformers.
  • Circular dichroism spectroscopy to analyze secondary structure changes.
  • Affinity capillary electrophoresis to assess interactions with amyloid-binding dyes.

Main Results:

  • Two distinct conformers of β2M were observed in aqueous buffers and upon treatment with organic solvents.
  • These nonnative conformations exhibited altered secondary structures (loss of β-sheets, gain of α-helices).
  • Nonnative β2M showed increased specific interactions with dyes like Congo red, indicative of amyloidogenic properties.

Conclusions:

  • Pre-fibrillar, nonnative conformations of β2M exist and can be induced by environmental factors.
  • These findings provide insights into early events in amyloidogenesis and potential targets for therapeutic intervention.
  • The study facilitates the development of methods to detect and inhibit pro-amyloidogenic protein conformations.

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