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Aggregation characteristics of ovalbumin in beta-sheet conformation determined by spectroscopy
Raimon Sabaté1, Joan Estelrich
1Departament de Fisicoquímica, Universitat de Barcelona, Catalonia, Spain. estelric@farmacia.far.ub.es
Abstract:
Protein misfolding and aggregation are involved in a number of the so-called "conformational" diseases (e.g., transmissible spongiform encephalopathies and Alzheimer disease). The development of rational strategies to interfere with aggregation is a potential therapeutic approach that requires complete knowledge of the aggregation process. We studied the aggregation of ovalbumin in beta-sheet conformation using mainly the spectral changes in the spectra of two dyes (Congo Red and pinacyanol) caused by the aggregates. We assumed a linear model of polymerization that fit to the experimental data. The critical aggregation constant, concentration of half-aggregation, nucleation parameter, growth parameter, and number of aggregation and free energy changes (total and per residue) were determined as aggregation-related parameters. Beta-Ovalbumin aggregates in a cooperative way. Moreover, the differences between such parameters obtained with Congo Red and pinacyanol suggest that each dye interacts with the protein in its own way.
Insights
Ovalbumin protein aggregation into beta-sheet structures was studied. Dye interactions revealed cooperative aggregation, crucial for understanding conformational diseases and developing therapeutic strategies.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Protein misfolding and aggregation are hallmarks of neurodegenerative conformational diseases.
- Understanding these aggregation processes is vital for developing targeted therapeutic strategies.
Purpose of the Study:
- To investigate the aggregation mechanism of ovalbumin into beta-sheet conformation.
- To quantify key aggregation parameters and understand dye-protein interactions.
Main Methods:
- Studied ovalbumin aggregation using spectral changes of Congo Red and pinacyanol dyes.
- Applied a linear polymerization model to experimental data for parameter determination.
Main Results:
- Determined critical aggregation constant, half-aggregation concentration, nucleation, and growth parameters.
- Quantified free energy changes and revealed that beta-ovalbumin aggregates cooperatively.
- Observed distinct parameter values for Congo Red and pinacyanol, indicating specific dye-protein interactions.
Conclusions:
- Beta-ovalbumin aggregation is a cooperative process.
- Different dyes interact uniquely with protein aggregates, influencing parameter determination.
- This study provides insights into protein aggregation relevant to conformational diseases.