Hydrolysis of soybean isoflavonoid glycosides by Dalbergia β-glucosidases

Abstract

Two β-glucosidases from the legumes Dalbergia cochinchinensis and Dalbergia nigrescens were compared for their ability to hydrolyze isoflavonoid glycosides from soybean. Both D. nigrescens and D. cochinchinensis β-glucosidases could hydrolyze conjugated soybean glycosides, but D. nigrescens β-glucosidase hydrolyzed both conjugated and nonconjugated glycosides in crude soybean extract more rapidly. The kinetic properties K m, kcat, and kcat/Km of the Dalbergia β-glucosidases toward conjugated isoflavonoid glycosides, determined using high-performance liquid chromatography, confirmed the higher efficiency of the D. nigrescens β-glucosidase in hydrolyzing these substrates. The D. nigrescens β-glucosidase could also efficiently hydrolyze isoflavone glycosides in soy flour suspensions, suggesting its application to increase free isoflavones in soy products. © 2007 American Chemical Society.