Isolamento e caracterização da lectina camptosemina extraída das sementes de Camptosema ellipticum
Abstract
Lectins are (glico) proteins of non immune origin able to cause cellular agglutination or
precipitation of glicoconjugates. Legume lectin refers to plant lectins that are found exclusively
in species of the Leguminosae family. A notable characteristic of legume lectins is that all their
proteins share tertiary structure consisting of a jelly-roll motif, which is basically composed by β
sheet, but present great variability the quaternary association. This variability is considered
responsible for conferring different degrees of stability to the legume lectins. This work presents
the isolation and characterization of the camptosemin, a protein of legume lectins family, isolated
from seeds of Camptosema ellipticum, a plant that belongs to the Brazilian open pasture.
Camptosemin found to be a tetrameric protein, whose protomers exhibits approximately
26 kDa. It was able to agglutinate erythrocyte of all ABO sanguineous types and it was showed
high affinity for N-acetylgalactosamin carbohydrate. Spectroscopic assays have demonstrated
that camptosemin is an extremely resistant protein against the thermal and chemical unfolding.
Through the analysis of the unfolding curves and the refolding assays, a model of two states for
the unfolding of the protein was proposed. According to this model, at the equilibrium, only
presents native tetramers and unfolded monomers. The obtained values of Tm and are
in agreement with the ones described for other lectins.
G O H Δ 2