Purification and partial characterization of alpha-D-mannosidase from Erythrina indica seeds

Alpha-D-Mannosidase (EC: 3.2.1.24), a glycoprotein with 8.6% carbohydrate was purified (26 fold purification) to homogeneity from Erythrina indica seeds, by gel filtration on Bio-Gel P-100 and affinity chromatography on Con-A CL Seralose. The enzyme had the molecular mass of 124 kDa and 127 kDa by gel filtration and SDS-PAGE, respectively. The optimum pH and temperature for enzyme activity were found to be 4.6 and 50 degrees C, respectively. The K(m) value for the enzyme was 2.1 mM for p-nitrophenyl-alpha-D-mannopyranoside. The enzyme activity was found to depend on the presence of Zn2+. Chemical modification studies revealed the involvement of tryptophan, serine and cysteine for enzyme activity.