Abstract:

The comparison among the activities of isoflavone-glucosidases isolated from 32 species of plants showed that chickpea (Cicer arietinum)β-glucosidase activity is the highest. Then the chickpea β-glucosidase was purified by 10.1 folds with the yield of 7.2% after ammonium sulphate precipitation, DEAE-Cellocuse -52 ion exchange and Sephadex G-100 gel filtration chromatography. This purified enzyme has a molecular weight of about 73.2 kD and two subunits. The optimum temperature, pH and Km towards genistin and daidzin of this enzyme are 45 ℃, 6.0, 11.0 μg/ml and 19.0 μg/ml, respectively. This β- glucosidase is stable at pH and temperature range of 4.0 to 6.5 and 30 to 45 ℃ respectively. Furthermore, this enzyme can effectively hydrolyse genistin and daidzin, but be strongly inhibited by Ag+, Hg2+ and D-glucono-δ-lactone at a concentration of 1 mmol/L.

Key words: soybean isoflavone-glucosidase, β-glucosidase, genistin, Cicer arietinum, enzymatic properties