Estudo dos componentes protéicos da peçonha da serpente Micrurus frontalis (serpentes: elapidae)

AUTOR(ES)

Karla Graziella Moreira

DATA DE PUBLICAÇÃO

2010

RESUMO

Coral snakes (Micrurus genus) venoms contain a wide spectrum of biologically active proteins and peptides. The major obstacle to study Micrurus venoms is the small amount of material that can be collected. Therefore, the biochemistry and pharmacology of components from coral snakes venoms are mostly unknown. In this study we describe the isolation, molecular mass determination, complete and partial amino acid sequencing of short and long -chain three-finger toxins, PLA2 and waprin isolated from Micrurus frontalis venom. Components were purified using multiple steps of RP-HPLC. Molecular masses were determined by MALDI-TOF and ESI ion-trap mass spectrometry. The amino acid sequences of toxins were determined by sequencing of overlapping proteolytic fragments by Edman degradation and by De novo sequencing. The three-finger toxins were named Frontoxin (FTx) I-VI. The amino acid sequences of FTx I, II, III and VI predict 4 conserved disulphide bonds and structural similarity to previously reported short-chain -neurotoxins. FTx IV and V each contained 10 conserved cysteines and share high similarity with long-chain - neurotoxins. At the frog neuromuscular junction FTx II, III and IV reduced miniature endplate potential amplitudes in a time-and concentration-dependent manner suggesting Frontoxins block nicotinic acetylcholine receptors. Fragments of isolated PLA2 were determined and share high similarity scores with PLA2 from other Elapids. The waprin member possesses four conserved disulfide bonds and showed high identity with waprin from Naja nigricollis venom. Because of the significant sequence similarity with WAPs, the molecule was named Miwaprin. Due the insufficient amount of purified FTx I, V, VI, PLA2s and Miwaprin, these toxins were not submitted to the biological assays. These are the first complete primary structure characterization of M. frontalis snake venom toxins.

ASSUNTO(S)

micrurus frontalis pla2 ciencias biologicas waprina neurotoxina

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