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Phosphophoryn, a biomineralization template protein: pH-dependent protein folding experiments
1Arthur Amos Noyes Laboratory for Chemical Physics, California Institute of Technology, Pasadena 91125.
Biopolymers
|April 1, 1994
Summary
Bovine dentine phosphophoryn (BDPP) undergoes pH-dependent folding and unfolding transitions. These structural changes are driven by electrostatic interactions within its polyelectrolyte regions, with intervening sequences acting as hinges.
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- Bovine dentine phosphophoryn (BDPP) is a polyelectrolyte protein.
- Understanding protein folding behavior is crucial for biological function.
Purpose of the Study:
- To investigate the pH-dependent protein folding behavior of BDPP.
- To elucidate the structural transitions of BDPP across a wide pH range.
Main Methods:
- Utilized one- and two-dimensional NMR spectroscopy for proton spin assignments.
- Performed pH titration experiments to analyze residue behavior.
- Analyzed 31P-NMR and 1H-NMR data to identify residue populations and conformational changes.
Main Results:
- Identified distinct populations of O-phosphoserine (PSer) and Asp residues.
- Observed pH-dependent resonance shifts in Ser, Gly, and Pro residues, indicating specific pKa values.
- BDPP exhibits a folded conformation at low pH, transitioning to more open conformations as pH increases due to electrostatic repulsion.
Conclusions:
- BDPP's structure is likely composed of homologous and heterologous sequences forming polyelectrolyte clusters.
- Intervening regions act as hinges, mediating folding-unfolding transitions driven by electrostatic interactions.
- The protein's conformation is dynamically regulated by pH, influencing its structural state.