RESUMO
The Vascular Endothelial Growth Factor "VEGF" plays a pivotal role in the stimulation of angiogenesis. The VEGF isoforms (A-D) and PlGF act in a coordinate fashion to develop the vascular network. Numerous proteins closely related in structure and function to VEGF-A have been reported and were grouped in the VEGF family. Some predators make use of VEGF-like molecules with devastating results for their prey. VEGF-E, investigated in 1994, is encoded by the parapoxvirus (Orf virus). VEGF-F is a common term designating molecules which were isolated from snake venom (also known as svVEGF). These proteins are disulphide-linked homodimers of 110 amino acids each and have a molecular weight of approximately 25 kDa. Their primary structures show approximately 50% identity to VEGF-A. However, unlike VEGF-A, they do not contain any N-linked glycosylation sites. They interact with heparin but have a different binding domain from that of VEGF-A. Among species, these svVEGFs vary extensively in amino acid sequences and in receptor-binding specificities towards endogenous VEGF receptors. Understanding the properties that determine the specificity of these interactions could improve our knowledge of the VEGF-receptor interactions. This knowledge is essential to the development of new drugs in angiogenesis. This knowledge is essential to the development of new drugs in angiogenesis.
Assuntos
Neovascularização Fisiológica/efeitos dos fármacos , Venenos de Serpentes/uso terapêutico , Fator A de Crescimento do Endotélio Vascular/uso terapêutico , Humanos , Fator A de Crescimento do Endotélio Vascular/fisiologiaRESUMO
Numerous toxins from scorpion venoms are much more toxic to insects than to other animal classes, and possess high affinity to Na+ channels. Many of them active on insects were purified from the venom of Buthus occitanus tunetanus. Using amino acid sequences of BotIT2 and RACE-PCR amplification (Rapid amplification of cDNA ends) technique, we isolated, identified and sequenced the nucleotide sequence from the venom glands of the scorpion Buthus occitanus tunetanus. The cDNA encodes a precursor of an insect toxin of 60 amino acid residues. The deduced nucleotide sequence toxin was identical to the determined amino acid sequence of BotIT2. BotIT2 is more similar to the excitatory toxins in its mode of action and to the depressant toxins in its primary structure.
Assuntos
Sequência de Bases/genética , Clonagem Molecular/métodos , Venenos de Escorpião/genética , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Western Blotting , DNA Complementar/genética , Eletroforese em Gel de Ágar , Eletroforese em Gel de Poliacrilamida , Expressão Gênica/genética , Insetos/efeitos dos fármacos , Dados de Sequência Molecular , Neurotoxinas/efeitos adversos , Neurotoxinas/química , Técnica de Amplificação ao Acaso de DNA Polimórfico , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Venenos de Escorpião/efeitos adversos , Venenos de Escorpião/química , Venenos de Escorpião/classificação , Venenos de Escorpião/isolamento & purificação , Escorpiões , Canais de Sódio/efeitos dos fármacos , Relação Estrutura-Atividade , TunísiaRESUMO
We report the use of recombinant scorpion toxin in the form of fusion protein as antigen for mice immunisation. The aim is to produce protective antisera against lethal activity of the venom from Tunisian scorpion Buthus occitanus tunetanus, responsible for several annually reported human cases of scorpion stings. The gene encoding Bot III (the most toxic alpha toxin of Buthus occitanus tunetanus) was fused to the sequence encoding synthetic ZZ domains of staphylococcal protein A. The construct ZZ-Bot III was expressed in the periplasm of E. coli as a fusion protein and purified by affinity chromatography. The recombinant fusion protein was characterized and used as antigen to generate antibodies in mice. The antibodies against the recombinant protein neutralize the toxic venom (10 LD50/ml) and also confer protection for immunized mice against antigenically related mammal toxins.