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Does domain swapping improve the stability of RNase A?
F Grant Pearce1, Michael D W Griffin, Juliet A Gerrard
1School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand. grant.pearce@canterbury.ac.nz
Biochemical and Biophysical Research Communications
|March 7, 2009
Summary
Self-assembling protein complexes, like bovine ribonuclease A (RNase A) oligomers, form very stable structures. However, their potential for biomaterial assembly may be limited by their tendency to revert to a monomeric state after unfolding.
Area of Science:
- Biomaterials Science
- Protein Chemistry
- Supramolecular Chemistry
Background:
- Self-assembling complexes offer potential as novel supramolecular biomaterials.
- Domain-swapped protein complexes, specifically bovine ribonuclease A (RNase A) oligomers, have not been extensively studied for biomaterial applications.
- RNase A can form stable domain-swapped dimers, trimers, and tetramers with retained catalytic activity.
Purpose of the Study:
- To characterize the physical properties of RNase A domain-swapped oligomers.
- To investigate the strength and stability of quaternary interactions in RNase A oligomers.
- To assess the potential of RNase A domain swapping for biomaterial assembly.
Main Methods:
- Analytical ultracentrifugation was employed to measure the dissociation of RNase A oligomers.
- Fluorescent tags were utilized to detect dissociation at very low protein concentrations (down to 250 pM).
- Thermal stability assays were performed to compare oligomeric and monomeric RNase A.
Main Results:
- RNase A oligomers form exceptionally tight complexes, showing no dissociation even at 250 pM concentrations.
- The thermal stability of RNase A oligomers is comparable to that of the monomeric enzyme.
- Upon thermal unfolding and subsequent cooling, RNase A refolded into its monomeric form, not the oligomeric state.
Conclusions:
- The quaternary structure of RNase A oligomers is highly stable, with tertiary structure being the primary determinant of overall protein stability.
- The inability of RNase A to reform oligomeric structures after thermal unfolding may restrict its utility in self-assembling biomaterial applications.
- Further research is needed to explore strategies for stabilizing domain-swapped structures for material design.
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