Related Experiment Videos
Myotoxic activity of an acidic phospholipase A2 isolated from Lachesis muta (Bushmaster) snake venom
A L Fuly1, S Calil-Elias, R B Zingali
1Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janiero, RJ, Brazil.
Abstract:
An acidic phospholipase A2 isolated from Lachesis muta snake venom denoted LM-PLA2, showed neither toxic nor anticoagulant activities in contrast to a potent inhibitory effect of collagen-induced platelet aggregation [Fuly, A.L., Machado. O.L.T., Alves, E.W. and Carlini, C.R., 1997. Thromb. Haemost 78, 1372-1380.]. Now, the myotoxicity induced by LM-PLA2 was investigated by using both in vivo and in vitro experiments. LM-PLA2 induced in vitro a dose- and time-dependent release of creatine-kinase (CK) from mouse Extensor Digitorium Longus (EDL) muscles and also increased the plasma CK activity in treated animals. Histopathological studies confirm myonecrosis of mouse skeletal muscles as a major effect. Edema could also be seen in muscle tissue. The amino-terminal sequence of LM-PLA2 (previously reported) indicates an aspartic acid residue located at position 49, together with other conserved amino acids present in the Asp-49 phospholipases, such as Tyr-28, Gly-30, Gly-32, His-48. Chemical modification of the protein moiety was also performed. Histidine alkylation with p-bromophenacyl bromide and lysine acetylation with acetic anhydride, abolished both indirect hemolytic and myotoxic activities of LM-PLA2. On the other hand, contrarily to what has been observed with several basic myotoxic phospholipases, the myotoxic effect induced by LM-PLA2 was not abolished by heparin.
Insights
Acidic phospholipase A2 (LM-PLA2) from Lachesis muta snake venom causes muscle damage (myotoxicity) and edema. Chemical modification of histidine and lysine residues abolished its myotoxic and hemolytic activities.
Area of Science:
- Biochemistry
- Toxicology
- Pharmacology
Background:
- Snake venom phospholipases A2 (PLA2s) exhibit diverse biological activities.
- Acidic PLA2 (LM-PLA2) from Lachesis muta venom lacks toxicity and anticoagulant effects but inhibits platelet aggregation.
- The myotoxic potential of LM-PLA2 remained uncharacterized.
Purpose of the Study:
- To investigate the myotoxicity of LM-PLA2 from Lachesis muta snake venom.
- To elucidate the role of specific amino acid residues in LM-PLA2's myotoxic activity.
Main Methods:
- In vivo and in vitro experiments were conducted.
- Creatine kinase (CK) release from mouse muscles and plasma CK activity were measured.
- Histopathological analysis of muscle tissue was performed.
- Chemical modifications (histidine alkylation, lysine acetylation) were applied to LM-PLA2.
Main Results:
- LM-PLA2 induced dose- and time-dependent creatine kinase release from mouse Extensor Digitorium Longus muscles.
- Increased plasma CK activity and histopathological evidence of myonecrosis and edema were observed in treated animals.
- Chemical modification of histidine and lysine residues abolished both indirect hemolytic and myotoxic activities of LM-PLA2.
- Unlike basic myotoxic PLA2s, LM-PLA2's myotoxicity was not inhibited by heparin.
Conclusions:
- LM-PLA2 is a myotoxic component of Lachesis muta snake venom.
- The presence of Asp-49 and conserved residues suggests a catalytic role in myotoxicity.
- Histidine and lysine residues are crucial for LM-PLA2's myotoxic and hemolytic activities.