An endo-β-glucosidase was isolated from Aspergillus niger grown on a medium containing rutin as the sole carbon source, and was partially purified by affinity chromatography. The enzyme was found to be extracellular. Its optimum pH was 3.4, and its optimum temperature 65°. KM values were 1 mM (PNPG) and 1.25 mM (geranyl-β-rutinoside), Vmax values were 0.22 μmol/min/mg protein (PNPG) and 0.08 μmol/min/mg protein (geranyl-β-rutinoside), and KI was 40 mM (glucose). The enzyme's activity was not inhibited by fructose, sucrose or SO2, and was enhanced by ethanol. No loss of activity was found after seven days at 50°. Mr determined by gel filtration was 120 000. Using polyacrylamide isoelectric focusing gel, a pI of 3.9 was obtained.
- Aspergillus niger, Vitis vinifera
- monoterpene glycosides