Isolation and characterization of three phospholipases A from the crotoxin complex

Area of Science:

• Biochemistry
• Toxicology
• Enzymology

Background:

• The crotoxin complex from Crotalus durissus terrificus venom contains multiple toxic components.
• Phospholipases A (phosphatide acyl-hydrolase, EC 3.1.1.4) are key enzymes involved in venom toxicity.

Purpose of the Study:

• To isolate and characterize phospholipase A isoenzymes from the crotoxin complex.
• To investigate the biochemical and toxicological properties of these enzymes and their interaction with crotapotin.

Main Methods:

• Purification of phospholipase A isoenzymes using carboxymethyl cellulose, Sephadex G-50 gel filtration, and DEAE-cellulose chromatography.
• Characterization via electrophoresis (cellogel, polyacrylamide, SDS-gel), immunoelectrophoresis, isoelectric focusing, and molecular weight determination (gel filtration, SDS-gel electrophoresis).
• Amino acid analysis (N- and C-terminal sequencing, methionine residue analysis) and enzymatic activity assays.

Main Results:

• Two basic phospholipase A isoenzymes were purified with high yields, exhibiting identical properties and toxicity.
• An acidic phospholipase A was isolated with lower specific enzymatic activity, found to be non-toxic and antigenically distinct.
• Crotapotin potentiated the toxicity and inhibited the basic phospholipases A but did not interact with the acidic isoform.

Conclusions:

• The crotoxin complex contains distinct basic and acidic phospholipase A isoenzymes with differing biochemical and toxicological profiles.
• Crotapotin plays a crucial role in modulating the activity and toxicity of specific phospholipase A isoforms.
• Homology was observed between these Crotalus phospholipase A isoenzymes and those from other sources, suggesting conserved structural and functional features.