[Purification and properties of two beta-glycosidases from Cicer arietinum L. with preferential specificity for biochanin A 7-beta-apiosylglucoside (author's transl)].

Four different beta-glycosidases have been separated from leaves of chick pea plants, Cicer arietinum L., by DEAE-cellulose chromatography. One is specific for isoflavone 7-beta-glucosides and has been described elsewhere. Two others showed very similar protein properties and identical catalytic activities. They have been further purified and both appeared as single, homogeneous protein bands after alkaline disc electrophoresis as well as isoelectric focusing. Isoelectric points are at pH 4.35 and 4,45, respectively. Both beta-glycosidases have molecular weights of 120000-140000 and have two subunits with identical molecular weights of 65 000. Both beta-glycosidases preferentially catalyze hydrolysis of diglycosides like biochanin A 7-beta-apiosyl(1 leads to 2)glucoside (Km=1.5 X 10(-4) M; V=10 mumol X min-1 X mg-1). The apiosylglucoside unit is liberated as an intact disaccharide. beta-Glucosides like biochanin A 7-beta-glucoside or 2-nitrophenyl glucoside are also efficiently hydrolyzed. These beta-glycosidases also possess transferase activity, but only when measured with isoflavone aglycones as acceptors. Transfer of the intact apiosylglucoside unit of biochanin A 7-beta-apiosylglucoside could be demonstrated. The enzymes have a pH optimum of 5.5. The beta-glycosidates are strongly inhibited by p-hydroxymercuribenzoate and Bromocondurite. Glucono-1,5-lactone, Ag and Hg2 showed only weak inhibition and Condurit B epoxide had no effect at all. A fourth beta-glycosidase activity from chick pea leaves shows no preferential activity for isoflavone 7-glycosides.