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Updated: Jul 19, 2026

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

Published on: November 21, 2013

pH-dependent self-assembly of polyalanine peptides.

Kalyan Giri¹, Nitai P Bhattacharyya, Soumen Basak

¹Chemical Sciences Division and Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata-700064, India.

Biophysical Journal

|October 17, 2006

Summary

Polyalanine expansions in PABP2 protein cause oculopharyngeal muscular dystrophy (OPMD). Longer peptides formed stable fibrils in alkaline conditions, suggesting a nucleation-controlled polymerization mechanism for this protein deposition disease.

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Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

Published on: August 20, 2018

Area of Science:

Biochemistry
Molecular Biology
Biophysics

Background:

Polyalanine expansions in the PABP2 protein are linked to oculopharyngeal muscular dystrophy (OPMD).
Protein misfolding and aggregation into insoluble inclusions in muscle tissues and cell nuclei are hallmarks of OPMD.
Understanding the factors influencing fibril formation is crucial for OPMD research.

Purpose of the Study:

To investigate the effect of solvent conditions and alanine repeat number on the fibril formation propensity of PABP2-derived peptides.
To explore the conformational properties and aggregation mechanisms of polyalanine peptides.
To assess the potential for designing novel materials using these self-assembling peptides.

Main Methods:

Synthesis of three peptides mimicking the N-terminal polyalanine segment of PABP2 with varying alanine repeat numbers (n=7, 11, 17).
Study of peptide conformational properties as a function of pH, particularly in alkaline conditions (pH >10).
Analysis of fibril formation kinetics using Thioflavin T (ThT) fluorescence assays and observation of growth patterns.

Main Results:

Longer peptides (11-ala and 17-ala) exhibited enhanced beta-sheet content and formed fibrils in alkaline media (pH >10) after 1-2 weeks.
Tyrosyl radical cross-linking to form dityrosine at high pH stabilized fibril growth.
Fibril formation followed a nucleation-controlled polymerization mechanism, evidenced by exponential growth kinetics and lag times.
Hierarchical self-assembly resulted in fractal-shaped growth patterns.

Conclusions:

Alanine repeat length and alkaline solvent conditions significantly influence PABP2 peptide fibril formation.
The observed fibrillation mechanism suggests a pathway relevant to protein deposition diseases like OPMD.
The fractal self-assembly patterns indicate potential applications in novel biomaterial design.