A yeast strain isolated in the laboratory from fruit juices was studied and classified as Candida sake. The strain produces an intracellular P-glucosidase when grown with cellobiose as the carbon source. The enzyme was purified 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 following treatment of the purified enzyme with sodium dodecyl sulfate. The enzyme exhibited optimum activity at 52 degreesC and pH 4.25 with citrate-phosphate 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-glucosidase was found to be tolerant to glucose inhibition with a K-i value of 0.2 mol/L.