Abstract

Maria Cristina Silva, Angelita Duarte Corrêa, Custódio Donizete dos Santos, Flávia Cristina Almeida Marcos and Celeste Maria Patto de Abreu

Lectins have various biotechnological applications including their use in agriculture as antimicrobials and pesticides. Lectin from manioc leaf powder has been extracted, partially purified and evaluated in terms of its haemagglutination activity and fungicidal properties against Fusarium oxysporum. Ground, dried and the entire leaves of Manihot esculenta (Cacao cultivar) were extracted with distilled water and the protein extract was concentrated by precipitation in 80% saturated ammonium sulphate solution. The concentrated protein solution was partially purified on a Sepharose column and the unbound protein fraction was submitted to native and denaturing polyacrylamide gel electrophoresis. Lectin from manioc leaf powder exhibited a haemagglutination (HU) activity of 0.5 HU/100 µl and was stable over a wide temperatures range (up to 70°C). Four protein bands (of 13, 58, 61, 64 kDa) were identified in the unbound protein fraction obtained by column chromatography, and the presence of a lectin was demonstrated by the determination of an HA value of 0.5 HU/100 µl. The concentrated protein solution was not, however, active against F. oxysporum at concentrations up to 100 µg/ml.