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The electrostatic basis for the interfacial binding of secretory phospholipases A2
D L Scott1, A M Mandel, P B Sigler
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticutt 06511.
Biophysical Journal
|August 1, 1994
Summary
Electrostatic forces are key for secretory phospholipases A2 binding to interfaces. Calcium ions enhance this enzyme
Area of Science:
- Biochemistry and structural biology
- Enzyme kinetics and interfacial binding
Background:
- Secretory phospholipases A2 (sPLA2) bind to lipid aggregates like micelles and membranes.
- Electrostatic forces are hypothesized to mediate initial enzyme-substrate aggregate interactions.
- This interfacial binding is distinct from substrate binding at the active site.
Purpose of the Study:
- To investigate the role of electrostatic forces in the interfacial binding of sPLA2.
- To calculate and analyze electrostatic potentials of various sPLA2 species.
- To identify potential interfacial binding regions on sPLA2.
Main Methods:
- Calculation of electrostatic potentials for 10 sPLA2 species.
- Utilized atomic coordinates from x-ray crystallography.
- Analyzed the effect of calcium ions on electrostatic properties.
Main Results:
- Most sPLA2 species exhibit significant electrostatic asymmetry (sidedness).
- Calcium ions accentuate this electrostatic asymmetry.
- The observed asymmetry suggests a specific interfacial binding region.
Conclusions:
- Electrostatic forces are critical for orienting and anchoring sPLA2 at interfaces.
- The calculated electrostatic sidedness aligns with experimental findings on binding regions.
- This study provides a molecular basis for understanding sPLA2 interfacial interactions.