Purificação, caracterização bioquímica e efeito na inibição de biofilmes bacterianos de uma lectina isolada da esponja marinha Aaptos sp.

Abstract

Belonging to the porifera phylum (from Latin porus, pore, + beast, bearer of), sponges are the most primitive multicellular animals on the planet. They are sessile, benthic, being predominantly marine. In recent decades, sponges have proved to be an abundant and promising source of bioactive compounds, such as lectins. Lectins can be defined as proteins/ glycoproteins of nonimmune origin that bind and/or precipitate carbohydrates and glycoconjugates and substances containing them, free in solution or on the cell surface, without changing the covalent structure of the glycosidic bonds, reversibly and not covalent. Thus, the objective of the present work was to purify, characterize biochemically and test possible biological activities of a lectin present in the marine sponge Aaptos sp. The novel lectin (AL - Aaptos Lectin) was isolated from the combination of affinity chromatography on Guar gum matrix followed by molecular exclusion chromatography on UPLC system. AL was able to agglutinate native and enzymatically treated rabbit erythrocytes and was inhibited by galactosides. The new protein is stable at neutral to alkaline pH, is thermolabile by totally losing its activity at 40 ° C, and its molecular mass determined by spectrometry was 13.655 ± 2 Da. According to circular dichroism the lectin consists of 28% α-helix, 26% β-sheet, and 46% random region. AL was nontoxic against artemia nauplii and was not able to inhibit bacterial biofilm formation but was able to reduce the number of viable E. coli bacteria cells. Further studies will be needed to elucidate the structure of the lectin and to discover possible biotechnological applications of the new protein.