Abstract
A β-rutinosidase, which was specific for releasing the disaccharide rutinose from the flavonoid glycoside rutin, was purified from Penicillium rugulosum IFO 7242. This enzyme had the molecular weight of 245,000, a very low optimum pH of 2.2, and the remarkable specificity that the glycosidase did not hydrolyze any other substrates like 4-nitrophenyl β-glucoside and cellobiose, but only rutin and isoquercitrin.