Related Experiment Videos
Conformational changes associated with activation of bee venom phospholipase A2
T Ahmed1, S M Kelly, A J Lawrence
1University of Glasgow, UK.
Journal of Biochemistry
|December 1, 1996
Summary
Bee venom phospholipase A2 (PLA2) activation by fatty acids involves a conformational change, not just hydrophobicity. This modification enhances catalytic and lytic activity by altering protein structure.
Area of Science:
- Biochemistry
- Enzymology
- Protein Conformation
Background:
- Bee venom phospholipase A2 (PLA2) has a binding site for long-chain fatty acids.
- Fatty acid binding can enhance PLA2 catalytic and lytic activity.
Purpose of the Study:
- To investigate the mechanism of PLA2 activation by fatty acids.
- To determine if activation is due to conformational changes or altered hydrophobicity.
Main Methods:
- Enzyme treatment with oleic acid and glutaraldehyde, followed by borohydride reduction.
- Kinetic studies of enzyme activity.
- Circular dichroism (CD) spectroscopy.
- Protein fluorescence spectroscopy.
- Binding studies.
Main Results:
- Reduction of glutaraldehyde-treated PLA2 with borohydride stabilized activation and allowed fatty acid removal, indicating activation is largely independent of oleic acid presence.
- Activation resulted from a conformational change, not increased hydrophobicity.
- CD spectra showed changes in secondary structure (increased alpha-helix and beta-sheet content).
- Fluorescence spectroscopy revealed changes in tryptophan residue exposure.
Conclusions:
- PLA2 activation by fatty acids is primarily due to a conformational change in the protein.
- This conformational change enhances catalytic activity without necessarily increasing membrane affinity.