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Two latent and two hyperstable polymeric forms of human neuroserpin
Stefano Ricagno1, Margherita Pezzullo, Alberto Barbiroli
1Dipartimento di Scienze Biomolecolari e Biotecnologie, Università di Milano, Milan, Italy.
Biophysical Journal
|November 18, 2010
Summary
Human neuroserpin undergoes distinct conformational changes at different temperatures, forming unique latent and polymeric structures. This research clarifies serpin polymerization, offering insights into protein behavior and disease mechanisms.
Area of Science:
- Biochemistry
- Structural Biology
- Neuroscience
Background:
- Human neuroserpin (hNS) is a nervous system-expressed serine protease inhibitor.
- Serpins feature a reactive center loop crucial for protease inhibition and latency.
- Pathological hNS mutants form polymers, but their organization remains debated.
Purpose of the Study:
- To biophysically characterize native human neuroserpin.
- To investigate the conformational transitions and resulting species of hNS.
- To elucidate the structural differences between hNS polymers.
Main Methods:
- Differential Scanning Calorimetry (DSC) to identify thermal transitions.
- Circular Dichroism (CD) spectroscopy to assess secondary structure changes.
- Size Exclusion Chromatography (SEC) and Transmission Electron Microscopy (TEM) for polymer characterization.
Main Results:
- Native hNS exhibits two distinct conformational transitions at 55°C and 85°C.
- These transitions yield different latent and polymeric forms with varying stabilities, sizes, and morphologies.
- The 85°C polymer displays increased intermolecular β-sheet content compared to the 45°C polymer.
Conclusions:
- hNS polymerization is more complex than previously understood, involving distinct conformational states.
- The findings reconcile contrasting views on serpin polymer organization.
- This study provides a foundation for understanding hNS-related neurological disorders.
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