Isolation, Purification and Characterization of β-1,3 Glucan Binding protein in the Serum of Mole Crab Emerita asiatica

Abstract

βGBP was identified in the serum of the mole crab, Emerita asiatica, which was purified by laminarin precipitation. It is followed by affinity chromatography on laminarin-Sepharose 6B. The purified protein’s carbohydrate-binding specificity was confirmed, and its electrophoretic and immunological properties were characterized. βGBP was observed as a single band in both native PAGE and isoelectric focusing, and its purity was validated by HPLC analysis. The protein exhibited dose-dependent agglutination of baker’s yeast, bacteria, erythrocytes, and enhanced serum prophenoloxidase (proPO) activity. It also demonstrated serine protease activity but not β-1,3-glucanase activity. The findings suggest that βGBP acts as a pattern recognition molecule with specificity for microbial β-1,3-glucan. Binding to this ligand triggers the prophenoloxidase cascade, likely via its intrinsic serine protease activity. βGBP exhibits both agglutinating and proteolytic functions, indicating it is a dual-purpose immune protein. The findings are evaluated for its evolutionary significance and homology with similar immune molecules in other invertebrates.