A lectin was purified from the hemolymph of Allomyrina dichotoma larvae by affinity chromatography on acid-treated Sepharose 4 B. The purified lectin showed two protein bands on polyacrylamide gel electrophoresis. These two lectin bands (allo A-I and -II) were separated by DEAE-Cellulofine column chromatography. By gel filtration on Sephadex G-100, the molecular weights of alto A-I and -II were estimated to be 65, 000 and 66, 500, respectively. On the other hand, by SDS-polyacrylamide gel electrophoresis after cross-linking of subunits with glutaraldehyde, they are estimated to be 38, 000 and 39, 000, respectively. On SDS-polyacrylamide gel electrophoresis, it was proved that both allo A-I and -II lectin consisted of two subunits, respectively. The molecular weights were 17, 500 and 20, 000 for allo A-I, and 19, 000 and 20, 000 for allo A-II. The isoelectric points of alto A-I and -II were estimated to be 6.4 and 5.9, respectively.
On double immunodiffusion, allo A-I and -II gave single precipitin lines, which fused completely with each other, against the antibody to crude allo A. The hemag-glutinating activity of allo A-I and -II was inhibited only by β-linked D-galactose such as lactose and lactulose.