A lectin was isolated from the pod saline extract of Caesalpinia tinctoria by dialoconcentration on Centripep-10 and affinity chromatography on chitin column. The purified lectin was partially characterized with respect to its biochemical and structural properties. It contains 8.3 % of carbohydrate and exhibited an agglutinating activity against human erythrocytes (ABO groups). Its amino acid composition was characterized by a great number of acidic and hydrophobic residues and the estimated molecular mass was 12.5 kDa. The presence of only one N-terminal amino acid sequence (D¹-V-P-A-Y-V-Y-V-H-F10-G-F-G-E-E-H-R -D-V-F20-D), showed the homogeneity of the purified lectin. The far-ultraviolet circular dichroism (CD) spectrum of lectin indicated that it contains 10 % a-helix, 38 % b-sheet, 28 % unordered form and 6 % of P II (poly-L-proline II helix conformation).
circular dichroism; Leguminosae; plant defense; pod; secondary structure
