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Dimeric character of a basic phospholipase A2 from cobra venom: experimental and modelling study.
J P Demaret1, S Chwetzoff, S Brunie
1Laboratoire de Biochimie (CNRS UA 240), Ecole Polytechnique, Palaiseau, France.
Protein Engineering
|December 1, 1990
Summary
Basic phospholipase A2 from Naja nigricollis venom forms a stable dimer without calcium. Structural modeling suggests specific amino acid changes, like Arg31, stabilize this dimeric form.
Area of Science:
- Biochemistry
- Structural Biology
- Venom Research
Background:
- Basic phospholipase A2 (PLA2) from Naja nigricollis venom exhibits dimerization in the absence of calcium ions.
- Understanding the structural basis of this dimerization is crucial for elucidating enzyme function and evolution.
Purpose of the Study:
- To investigate the structural possibility of phospholipase A2 dimerization.
- To build and validate three-dimensional models of monomeric and dimeric N. nigricollis PLA2.
Main Methods:
- Homology modeling based on bovine pancreatic and Crotalus atrox venom PLA2 structures.
- Graphical model building, incorporating loop deletion for dimeric model construction.
- Molecular mechanics and molecular dynamics simulations for model validation.
Main Results:
- Stable three-dimensional models of monomeric and dimeric N. nigricollis PLA2 were successfully generated.
- The dimeric model demonstrated stability in the absence of calcium ions.
- The presence of Arg31, replacing a hydrophobic residue, was identified as a key contributor to dimeric stability.
Conclusions:
- The structural modeling supports the hypothesis of phospholipase A2 dimerization in N. nigricollis venom.
- Specific amino acid substitutions, particularly Arg31, play a significant role in stabilizing the dimeric form.
- These findings provide structural insights into the dimerization behavior of snake venom PLA2s.