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Maximal stabilities of reversible two-state proteins.
Sandeep Kumar1, Chung-Jung Tsai, Ruth Nussinov
1Laboratory of Experimental and Computational Biology, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA.
Biochemistry
|April 24, 2002
Summary
Globular proteins are maximally stable around room temperature due to the hydrophobic effect. This study confirms this, finding 20 proteins are most stable near 20°C, regardless of their origin.
Area of Science:
- Biophysics
- Protein Folding
- Thermodynamics
Background:
- The hydrophobic effect is a primary driver of protein folding.
- It is strongest around room temperature, suggesting maximal protein stability at this temperature.
- This hypothesis has lacked experimental validation.
Purpose of the Study:
- To experimentally verify the hypothesis that globular proteins exhibit maximal stability around room temperature.
- To analyze thermodynamic data for a diverse set of proteins.
Main Methods:
- Collected and analyzed experimental thermodynamic data for 31 proteins exhibiting reversible two-state folding.
- Focused on proteins with transitions near neutral pH.
Main Results:
- 20 out of 26 unique proteins showed maximal stability around room temperature (average 20°C).
- Maximal stability was independent of protein size, fold, origin (psychrophile, mesophile, thermophile), or melting temperature.
- Correlations in thermodynamic parameters suggest adaptation to organismal living temperatures.
Conclusions:
- Experimental data supports the paradigm of maximal protein stability around room temperature.
- Protein size may have an upper limit for maximal thermodynamic stability.
- Deviations from room temperature stability may relate to heat capacity changes, hydrophobic effect strength, or electrostatic contributions.