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The fluorescent characterization of the polymerized microtubule-associated protein Tau
1Laboratory of Visual Information Processing, Institute of Biophysics, The Chinese Academy of Sciences, Beijing, PR China.
Abstract:
A new fluorescence formed while microtubule-associated protein tau was incubated at 25 and 37C for hours, with its maximum excitation at 230 and 280 nm, respectively. The fluorescence completely formed after tau was incubated in phosphate buffer and Tris-HCl buffer for approximately 20 h, with a relaxation phase about 2-4 h. The light scattering of the sample solution improved during formation of the fluorescence when tau was incubated. Both the fluorescence and tau oligomers did not form when tau was incubated in the buffers containing DTT. On the other hand, heparin improved both tau aggregation and the fluorescence formation. It suggests that the fluorescence comes from tau polymerization, which may follow the mechanism of tyrosine-tyrosinate emission for a protein not containing any tryptophan residues. This new fluorescence could be used as a probe to tau polymers.
Insights
Researchers discovered a new fluorescence emitted by microtubule-associated protein tau during polymerization. This fluorescence, linked to tau aggregation, could serve as a novel probe for detecting tau polymers.
Area of Science:
- Biochemistry
- Neuroscience
- Protein Chemistry
Background:
- Microtubule-associated protein tau (tau) is implicated in neurodegenerative diseases.
- Understanding tau aggregation mechanisms is crucial for developing therapeutic strategies.
- Novel methods for detecting tau polymers are needed.
Purpose of the Study:
- To investigate the formation of a new fluorescence during tau incubation.
- To characterize the properties of this novel fluorescence.
- To explore the relationship between tau polymerization and fluorescence emission.
Main Methods:
- Incubation of tau protein at different temperatures (25°C and 37°C).
- Spectroscopic analysis to determine fluorescence excitation maxima.
- Light scattering measurements to assess aggregation.
- Incubation in various buffer conditions (phosphate buffer, Tris-HCl, with DTT, with heparin).
Main Results:
- A new fluorescence formed upon tau incubation, with excitation maxima at 230 and 280 nm.
- Fluorescence formation correlated with increased light scattering, indicating aggregation.
- Dithiothreitol (DTT) inhibited both fluorescence and oligomer formation.
- Heparin promoted both tau aggregation and fluorescence.
- The fluorescence mechanism may involve tyrosine-tyrosinate emission.
Conclusions:
- A novel fluorescence is generated during tau polymerization.
- This fluorescence is dependent on aggregation conditions and can be modulated by heparin and DTT.
- The findings suggest a potential role for tyrosine-tyrosinate emission in tau fluorescence.
- This new fluorescence can serve as a sensitive probe for detecting tau polymers.