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Compressibility-structure relationship of globular proteins.
Biochemistry
|October 21, 1986
Summary
Protein compressibility, a measure of internal volume fluctuations, is linked to protein structure and amino acid composition. Higher compressibility correlates with increased partial specific volume and hydrophobicity, impacting thermal stability.
Area of Science:
- Biophysics
- Physical Chemistry
- Protein Science
Background:
- Adiabatic compressibility (βs) is a key physical property of proteins.
- Understanding protein compressibility is crucial for elucidating molecular dynamics and stability.
Purpose of the Study:
- To determine the adiabatic compressibility of globular proteins in water.
- To investigate correlations between protein compressibility and structural parameters, including amino acid composition.
- To derive empirical equations for predicting protein compressibility.
Main Methods:
- Sound velocity measurements at 25°C to determine adiabatic compressibility (βs).
- Statistical analysis of compressibility data for 25 proteins.
- Examination of correlations with partial specific volume, hydrophobicity, helix content, and amino acid composition.
Main Results:
- Most proteins exhibited positive adiabatic compressibility (βs), indicating significant internal compressibility.
- Intrinsic protein compressibility is comparable to that of ice.
- Adiabatic compressibility (βs) increases with partial specific volume and hydrophobicity.
- Specific amino acid residues (Leu, Glu, Phe, His) increase βs, while others (Asn, Gly, Ser, Thr) decrease it.
- Volume fluctuations were quantified (30-200 mL/mol).
Conclusions:
- Protein compressibility is influenced by structural features and amino acid composition.
- Derived empirical equations can estimate adiabatic compressibility (βs) from amino acid sequences.
- Protein volume fluctuations, revealed by compressibility, may enhance thermal stability.