Chitin-binding vicilin from
Enterolobium contortisiliquum seeds was purified by ammonium sulfatefollowed by gel filtration on Sephacryl 300-SH and on Sephacryl 200-SH. The vicilin, called EcV, isa dimeric glycoprotein composed of 1.03% carbohydrates and a
Mr of 151 kDa, consisting of twosubunits of
Mr of 66.2 and 63.8 kDa. The EcV homogeneity was confirmed in a PAGE where it wasobserved to be a unique acid protein band with slow mobility in this native gel.
E. contortisiliquumvicilin (EcV) was tested for anti-insect activity against
C.
maculatus and
Zabrotes subfasciatus larvaeand for phytopathogenic fungi,
F.
solani and
C.
lindemuntianum. EcV was very effective against bothbruchids, producing 50% mortality for
Z. subfasciatus at an LD
50 of 0.43% and affected 50% of thelarvae mass with an ED
50 of 0.65%. In artificial diets given to
C. maculatus, 50% of the larvae masswas affected with an ED
50 of 1.03%, and larva mortality was 50% at LD
50 of 1.11%. EcV was notdigested by midgut homogenates of
C. maculatus and
Z. Subfasciatus until 12 h of incubation, andat 24 h EcV was more resistant to
Z. subfasciatus larval proteases. The binding to chitin present inlarvae gut associated to low EcV digestibility could explain its lethal effects. EcV also exerted aninhibitory effect on the germination of
F.
solani at concentrations of 10 and 20
g mL-
1. The effectof EcV on fungi is possibly due to binding to chitin-containing structures of the fungal cell wall.