Evaluation of neurotoxic effects of BtnTX-II isoforms (Bj-IV and Bj-V) from Bothrops jararacussu on mouse phrenic nerve-diaphragm preparation when catalytic activity is inhibited by differently crotapotins crotalics. 

¹Bonfim, V.L., ¹Ponce-Soto, L.A., ¹Fagundes F.H.R., ¹Damico, D.C.S., ²Rodrigues-Simioni, L. and ¹Marangoni. S.

1 Departament of Biochemistry Institute of Biology and 2 Departament of Pharmacology-FCM-UNICAMP – Brazil.

In this work, we evaluated the neurotoxic effects of the isoforms of BthTX-II PLA2 (Bj-IV and Bj-V) from Bothropsjararacussu when catalytic activity was inhibited by isoforms of the crotapotins from Crotalusdurissus collilineatus on mouse phrenic nerve-diaphragm preparation. The purification of Bothropsjararacussu PLA2, made on one step, using HPLC ion-exchange chromatography (Protein Pack SP 5 PW-Waters) and ammonium bicarbonate buffer showed the presence of eight peaks denominated as Bj-I to Bj-VIII. The Bj-IV and Bj-V fractions were subjected to the preparative RP HPLC to further purification. The biochemical analysis of these new basics PLA2s isoforms (Bj-IV and Bj-V) showed a high enzymatic activity but when incubates together with the isoforms of crotapotins (F3 and F4) (molar reason 1:1) this activity was inhibited. The catalytic activity was inhibited but the neurotoxic activity wasn’t then the Bj-IV and Bj-V was able to take a blockage activity on the mouse neuromuscular junction, in the concentration of 50 and 100 mg/ml. Our results showed that catalytic activity of the Bj-IV and Bj-V apparently does not interfere with neurotoxic activity, demonstrating the possible presence of a specific domain for the effect pharmacological (Ponce-Soto, L.A., et al., 2002; Yi-Hsuan Chen, et al., 2004). We demonstrate the neurotoxic effect is not dependent directly of the enzymatic activity.

Financial Support: CAPES and FAPESP

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