Immunocytochemical and biochemical detection of alpha-L-fucosidase in Trypanosoma cruzi

The aim of the present study was to demonstrate the presence of alpha-L-fucosidase in Trypanosoma cruzi. Immunocytochemical and biochemical techniques were used to localize and characterize a membrane-associated, neutral-pH-optimum, alpha-L-fucosidase from the parasite. Light and electron microscopy localized the alpha-L-fucosidase specifically on the surface of the parasite and on membranes in the posterior region of the epimastigote stage. Although much less intense, labeling was also detected on the surface of trypomastigotes. At least 50% of the alpha-L-fucosidase activity was associated with epimastigote membrane solubilized with 1 M NaCl or 1% Triton X-100, suggesting that alpha-L-fucosidase is peripherally associated with membranes. The enzyme from epimastigotes had a neutral pH optimum (near 7) but displayed low specific activity when p-nitrophenyl-alpha-L-fucoside was employed as substrate (0.028 U/mg protein for epimastigotes and 0.015 U/mg protein for tissue culture-derived trypomastigotes). Polyacrylamide gel electrophoresis and Western blotting analysis both showed an expected 50-kDa polypeptide which was immunoreactive with anti-alpha-L-fucosidase antibodies.

Streptococcus anginosus como agentes de infeção em Humanos: um estudo epidemiológico numa taxonomia em mudança

Dissertação para obtenção do grau de Mestre em Microbiologia Médica

Xyloglucan Octasaccharide XXLGol Derived from the Seeds of Hymenaea courbaril Acts as a Signaling Molecule1

Treatment of the xyloglucan isolated from the seeds of Hymenaea courbaril with Humicola insolens endo-1,4-β-d-glucanase I produced xyloglucan oligosaccharides, which were then isolated and characterized. The two most abundant compounds were the heptasaccharide (XXXG) and the octasaccharide (XXLG), which were examined by reference to the biological activity of other structurally related xyloglucan compounds. The reduced oligomer (XXLGol) was shown to promote growth of wheat (Triticum aestivum) coleoptiles independently of the presence of 2,4-dichlorophenoxyacetic acid (2,4-D). In the presence of 2,4-D, XXLGol at nanomolar concentrations increased the auxin-induced response. It was found that XXLGol is a signaling molecule, since it has the ability to induce, at nanomolar concentrations, a rapid increase in an α-l-fucosidase response in suspended cells or protoplasts of Rubus fruticosus L. and to modulate 2,4-D or gibberellic acid-induced α-l-fucosidase.