Purification, physicochemical characterization and biological properties of a lectin from Erythrina velutina forma aurantiaca seeds.
A lectin was purified from seeds of Erythrina velutina forma aurantiaca by affinity chromatography on cross-linked guar gum. The lectin is a potent agglutinin for human (minimal concentration of protein able to cause visible agglutination of a 2% erythrocyte suspension varying from 1 to 4 micrograms/ml), rabbit (4 micrograms/ml) and chicken erythrocytes (8 micrograms/ml) but presented low activity against cow (250 micrograms/ml) or sheep (333 micrograms/ml) blood cells. Hemagglutination of human O+ erythrocytes was inhibited by D-lactose (0.2 mM) > D-galactose (0.8 mM) > D-raffinose (2.1 mM). At pH 7.5, chromatography on a Superose 12 HR 10/30 column showed that the lectin was primarily a dimer (56.0 kDa) composed of two identical subunits (31.6 kDa each). A small amount of a tetrameric form was also apparently present. The lectin is a glycoprotein (7.3% carbohydrate), has a pI of 4.5, contains high levels of acidic (Asp and Glu, 64.2 and 51.6 residues/mol, respectively) and hydroxy amino acids (Ser and Thr, 42.9 and 38.5 residues/mol, respectively) but relatively low amounts of sulfur amino acids (Cys and Met, 1.0 and 5.0 residues/mol, respectively) and has an N-terminal sequence of Val-Glu-Thr-Ile/Leu-Pro-Phe-Ser. Its hemagglutinating activity was abolished by heating at 70 degrees C for 10 min. The activation energy (delta G') required for denaturation measured by loss of hemagglutination activity was 24.87 kcal/mol. In rats, the purified lectin (100 micrograms) induced neutrophil migration into the peritoneal cavity (3.7 +/- 0.6 x 10(6) neutrophils/ml) or into the air pouch (2.75 +/- 0.25 x 10(6) neutrophils/ml), 8 and 10 times greater than the negative control, respectively.
Moraes
S M
SM
Departamento de Bioquimica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Brasil.
Cavada
B S
BS
Moreira
R A
RA
Roque-Barreira
M C
MC
Santos-de-Oliveira
R
R
Pinto
V P
VP
Oliveira
J T
JT
D000818:Animals; D001938:Brazil; D004895:Erythrina / Q000737:chemistry*; D006801:Humans; D037102:Lectins / Q000737:chemistry* / Q000302:isolation & purification; D037121:Plant Lectins; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar; D012639:Seeds / Q000737:chemistry
D037102:Lectins; D037121:Plant Lectins