DEGRADATION OF RUTIN BY ASPERGILLUS FLAVUS. PURIFICATION AND CHARACTERIZATION OF RUTINASE

Abstract

Aspergillus flavus produces an adaptive glycosidase (rutinase) that hydrolyzes rutin to quercetin and rutinose. Production of rutinase occurs when the mold is grown on the glycosides rutin, hyperosid, and naringin, and on the aglycones quercetin, kaempferol, rhamnetin, 2,4-dihydroxybenzoic acid, and 3,4-dihydroxyphenylacetic acid, but not when grown on glucose, galactose, rhamnose, or rutinose. Rutinase, after partial purification, is relatively stable when stored at −20 °C, and is most stable and most active at pH 5.6. The enzyme is quite specific, hydrolyzing the 5-glucoside of sakuranetin, the 3-rutinoside and 3-galactoside of quercetin, but not the 3-L-rhamnoside nor any of the common glycosides. The hydrolysis of rutin is carried to completion aided by the insolubility of the aglycone quercetin in water.