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Conformational changes in cubic insulin crystals in the pH range 7-11
1Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02254-9110.
Biophysical Journal
|November 1, 1992
Summary
Protein charge distribution significantly alters protein structure, influencing conformational changes in insulin. These pH-dependent shifts are crucial for understanding protein function and electrostatically triggered reactions.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Dynamics
Background:
- Protein conformation is influenced by charge distribution.
- Understanding these changes is key to protein function.
Purpose of the Study:
- To investigate the effect of pH-induced charge variations on bovine cubic insulin conformation.
- To correlate structural changes with monovalent cation binding.
Main Methods:
- X-ray crystallography of bovine cubic insulin across a pH range (7-11).
- Data collection beyond 2-A resolution with R factors from 0.16 to 0.20.
- Analysis of protein and solvent atom positions and residue conformations.
Main Results:
- Approximately 30% of residues changed conformation with pH variations.
- Conformational switching of A5 Gln and B10 His correlated with cation binding.
- Observed alternative positions for B25 Phe and A21 Asn at pH 11.
Conclusions:
- Protein conformational changes are loosely coupled and influenced by charge distribution.
- pH-dependent conformational shifts are analogous to electrostatically triggered protein reactions.
- These findings provide insights into the mechanisms of protein functional dynamics.