**45. Isoflavone conjugate-hydrolyzing beta-glucosidase**

Soybeans excrete from the roots isoflavones, which are involved in plant-microbe inter‐ actions such as symbiosis and as a defense against infections. The release of free isofla‐ vones from their conjugates, the latent forms, is catalyzed by an isoflavone conjugatehydrolyzing beta-glucosidase. The purified enzyme, isoflavone conjugate-hydrolyzing beta-glucosidase from (GmICHG), is a homodimeric 116-Da glycoprotein capable of di‐ rectly hydrolyzing genistein 7-O-(6 ''-O-malonyl-beta-d-glucoside) to yield free genistein. GmICHG cDNA is highly expressed in the seedling roots but only very weakly in coty‐ ledons and hypocotyls. The enzyme is exclusively localized in the cell wall and intercel‐ lular space of seedling roots, especially in the cell wall of root hairs. GmICHG is a member of glycoside hydrolase family 1 [49].
