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Master's Dissertation
DOI
https://doi.org/10.11606/D.60.2014.tde-27052014-091302
Document
Author
Full name
Priscila Carmanhan Lima
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2014
Supervisor
Committee
Braga, Eliane Candiani Arantes (President)
Araújo, Heloisa Sobreiro Selistre de
Rosa, Jose Cesar
Title in Portuguese
Isolamento e caracterização estrutural e funcional de uma nova toxina da peçonha do escorpião Tityus serrulatus
Keywords in Portuguese
citocinas
escorpião
Tityus serrulatus
toxina
Ts19 frag I.
Abstract in Portuguese
Envenenamentos por animais peçonhentos são frequentes e quase 35% dos acidentes são ocasionados por escorpiões, especialmente por Tityus serrulatus. A peçonha do escorpião amarelo Tityus serrulatus tem despertado o interesse médico e científico por ser uma mistura complexa de mucopolissacarídeos, inibidores de proteases, histamina, neurotoxinas, entre outros componentes. As neurotoxinas são as principais responsáveis pelos sintomas do envenenamento, por possuírem alta afinidade e seletividade para canais iônicos sensíveis à voltagem. Além de induzirem a liberação de neurotransmissores, as neurotoxinas também são capazes de estimular a liberação de citocinas, principalmente nos casos de envenenamento de maior gravidade. Os objetivos deste trabalho focaram o isolamento e a caracterização de uma nova toxina, denominada Ts19 fragmento I (Ts19 frag I) presente nas frações VII e VIII obtidas por cromatografia da peçonha de Tityus serrulatus em CM-celulose-52. Entre os componentes preponderantes destas frações estão a Ts4, um peptídeo não tóxico que induz reações alérgicas, e a Ts3-KS, que interage com canais para sódio e foi capaz de induzir a liberação de IL-6. As frações VII e VIII foram aplicadas em coluna de fase reversa C18 (4,6 x 250 mm) e os picos 19, 22 (Ts19 frag I) e 23 foram recromatografados em coluna C18 (2,1 x 250 mm). O sequenciamento por degradação de Edman permitiu a determinação de 57 resíduos de aminoácidos da Ts19 frag I, incluindo 6 resíduos de cisteína. Esta proteína mostrou compartilhar um elevado grau de identidade sequencial com outras toxinas que atuam em canais para K+ depositadas em bancos de dados. Sua massa molar íntegra de 6.571,3165 Da foi determinada por espectrometria de massas. Os ensaios funcionais em células de linhagem de macrófagos peritoneais demonstraram que a Ts19 frag I (50 ?g/mL) estimulou a liberação de óxido nítrico, IL-6 e não foi citotóxica na dose utilizada. Um ensaio para verificar a atividade hemolítica da Ts19 frag I também foi realizado e nas concentrações de 25 ?g/mL e 50 ?g/mL esta não demonstrou atividade citolítica. Nas frações VII e VIII também foram encontradas a Ts2, como um contaminante do pico 22, e a Ts19 frag II, cujo precursor é a Ts19 frag I. A Ts19 frag II presente no pico 19 foi sequenciada e mostrou-se contaminada com a Ts19 frag I.
Title in English
Isolation and structural and functional characterization of a novel toxin from Tityus serrulatus scorpion venom
Keywords in English
cytokines
scorpion
Tityus serrulatus
toxin
Ts19 frag I
Abstract in English
Poisonings by venomous animals are frequent and almost 35 % of the accidents are caused by scorpions, especially by Tityus serrulatus. The venom of the yellow scorpion Tityus serrulatus has aroused scientific and medical interest, since it is a complex mixture of mucopolysaccharides, protease inhibitors, histamine, neurotoxins and other components. The neurotoxins are the main responsible for the symptoms of poisoning by having high affinity and selectivity for voltage-sensitive ion channels. In addition to inducing neurotransmitter release, neurotoxins are also able to stimulate the release of cytokines, especially in cases of severe poisoning. The objectives of this study focused on the isolation and characterization of a novel toxin, named Ts19 fragment I (Ts19 frag I) present in fractions VII and VIII obtained by chromatography of Tityus serrulatus venom on CM-cellulose-52 column. Among the predominant components of these fractions are Ts4, a non-toxic peptide that induces allergic reactions, and Ts3-KS, which interact with sodium channels and was able to induce the release of IL-6. Fractions VII and VIII were applied to C18 reverse phase column (4.6 x 250 mm) and the peaks 19, 22 (Ts19 frag I) and 23 were rechromatographed on C18 (2.1 x 250 mm) column. Sequencing by Edman degradation allowed the determination of 57 amino acid residues of Ts19 frag I, including six cysteine residues. This protein showed to share a high degree of sequence identity with other toxins acting on K+ channels deposited in databases. Its full molar mass of 6.571,3165 Da was determined by mass spectrometry. The functional assays in cell line of peritoneal macrophages showed that Ts19 frag I (50 ?g/mL) stimulated the release of nitric oxide, IL-6 and was not cytotoxic in the dose used. A test to verify the hemolytic activity of Ts19 frag I was also performed and concentrations of 25 ?g/mL and 50 ?g/mL of toxin showed no cytolytic activity. In the fractions VII and VIII were also found Ts2, as a contaminant of the peak 22, and Ts19 frag II, whose precursor is the Ts19 frag I. The Ts19 frag II present in peak 19 was sequenced and showed to be contaminated with Ts19 frag I.
 
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Publishing Date
2014-11-18
 
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