Purification and characterization of an intracellular beta-glucosidase from a Candida sake strain isolated from fruit juices

A yeast strain isolated in the laboratory from fruit juices was studied and classified as Candida sake. The strain produces an intracellular P-glucosi dase when grown with cellobiose as the carbon source. The enzyme was purifi ed by ion-exchange chromatography and gel filtration. The molecular mass of the purified intracellular P-glucosidase, estimated by gel filtration, was 240 kDa. The tetrameric structure of the P-glucosidase was determined foll owing treatment of the purified enzyme with sodium dodecyl sulfate. The enz yme exhibited optimum activity at 52 degreesC and pH 4.25 with citrate-phos phate buffer. The enzyme was active against soluble glycosides with the (1 -->4)-beta configuration, and from Lineweaver Burk plots, a K-m value of 6. 9 mmol/L was found for p-nitrophenyl-beta -D-glucopyranoside. The P-glucosi dase was found to be tolerant to glucose inhibition with a K-i value of 0.2 mol/L.