Isolation and biochemical and functional characterization of a lectin from Bothrops atrox snake venom.

Author(s)

Elaine de Paula Mendonça Franqueiro

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2007-08-31

Examining board members

Suely Vilela; Eliane Candiani Arantes Braga; Jose Roberto Giglio

• Advisor: Suely Vilela

Abstract

The aim of this work was the analysis of structural and biological aspects of a B. atrox venom lectin, named galatrox. The galatrox purification involved two chromatographic steps, starting with an affinity column of Lactosyl-Sepharose followed by application of the retained material on a Lactosyl-Sepharose gel (LacR) in Sephadex G-25 column. The purification steps were monitored by absorbance at 280nm and SDSPAGE. Galatrox samples were submitted to digestion in situ with trypsin and the sequencing mass of the obtained peptides were determined by mass spectrometry (MALDI-TOF-MS and ESI-CID-MS/MS). The N-terminal sequence of amino acids from galatrox was obtained by automatized Edman degradation (PROCISE-491®). The lectin activity of this protein was characterized by human erytrocytes agglutination test in presence or absence of different carbohydrates as lactose (4mM) and galactose (20mM), EDTA (5mM) and heat. The mast cells degranulation was determined by -hexosaminidase release in RBL-2H3 cells sensibilized with anti-DNP IgE and challenged with galatrox, crude venom in a non retained fraction in Lactosyl-Sepharose (Lac-nR) , HAS-DNP (positive control) or PBS (negative control). The apoptosis and/or necrosi induced level in treated RBL- 2H3 cells with galatrox was evaluated using AnnexinV and/or Propidium iodide and analysed by flow citometry (FACSCanto®) with the help software (CBA-DIVA®). The camptotecin was used with apoptosi/necrosi reference. The edematogenic was tested in mice by the intraplantar injection of galatrox, Lac-nR fraction, crude venom and PBS. SDS-PAGE analyse indicated that the galatrox preparations were homogenous and contained a single band of 14,000 or 28,000 relative molecular weight showed in reducting or non-reducting conditions, respectively. N-terminal amino acid sequence was determined as following: NNXPQDWLPMNGLXYKIFD, and some internal amino acid sequence was obtained which correspond to KDFSWEWTDR and GHSEVWLGLWDK. The hemagglutination activity of this lectin was dose dependent and inhibited by EDTA (5mM), heating (100ºC/10min) and lactose (32mM, 16mM, 8mM, 4mM, 2mM, 1mM, 0,5mM). In the other hand, the crude venom and Lac-nR fraction, this lectin was not edematogenic nor promoted apoptosis and necrosi of RBL-2H3 cells. The galatrox induced a discret mast cells degranulation compared with crude venom and Lac-nR fraction. Based in obtained datas is suggested that galatrox is a homodimeric lectin with relative molecular mass of 28,000, -galactoside bindings and that shows structural similarity with other Ctype lectins from Bothrops ssp. venom. Even more the galatrox showed to be a weak proinflamatory agent and did not induced significant apoptotic and necrotic effect. Finally this work would contribute to better understanding of the biological impact that the lectin presence in venom and in poisonings as well in the generation of a new biotechnological products. (AU)