Poster 233 - Inhibitory effect of DM64, a protein from Didelphis marsupialis serum, on the activities

Poster 233. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.592.

Inhibitory Effect Of DM64, A Protein From Didelphis marsupialis Serum, On The Activities Of Crotalid Snake Venom Myotoxic Phospholipases A2

Rocha, S.L.G.^3,4; Angulo,Y.^1,2; Neves-Ferreira, A.G.C.³; Domont, G.B.^{4; Gutiérrez, J.M.¹}; Lomonte, B.¹; Perales,J.³

1 Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica; 2 Departamento de Bioquímica, Escuela de Medicina, Universidad de Costa Rica, San José, Costa Rica; 3 Departamento de Fisiologia e Farmacodinmica, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brasil; 4 Departamento de Bioquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.

Bothrops snake venoms are known to induce local tissue damage such as hemorrhage and myonecrosis. The opossum Didelphis marsupialis is resistant to these snake venoms and has natural venom inhibitors in its plasma. This study evaluated the interaction between DM64, an antimyotoxic protein from opossum serum, and several myotoxins from crotalid snake venoms. DM64 is an acidic protein showing 15% glycosilation and with a molecular mass of 63,659 Da. The inhibitor formed non-covalent complexes, by affinity chromatography, with myotoxins I and III (Asp-49 PLA2) and myotoxins II and IV (Lys-49) from B.asper, myotoxins I and II from A.nummifer, myotoxin II from C.godmani, bothropstoxins I and II from B.jararacussu and piratoxin from B.pirajai (the last three toxins were gently supplied by Dr. J.R. Giglio). DM64 neutralized both the in vivo myotoxicity and the in vitro cytotoxicity of myotoxins from crotalid snake venoms, but did not inhibit the PLA2 activity of myotoxins I and III from B.asper. In contrast to the myotoxins described so far, the metalloproteinases atrolisin and jararhagin did not form complexes with DM64. These results confirm that DM64 interacts specifically with myotoxins. Previous studies on a synthetic peptide derived from the cationic/hydrophobic sequence 115-129 (KKYKAYFKFKCKK) of the Agkistrodoncontortrix laticinctus myotoxin has been shown to exert direct cytotoxic activity upon C2C12 cell cultures. DM64 did not inhibit the lytic action of this peptide upon these myoblast cells, suggesting it may interact with another region of the myotoxin.