Abstract
An enzyme which lysed viable yeast cells was purified about 75-fold from the culture fluid of Arthrobacter luteus by procedures including salting out with ammonium sulfate and Biogel CM-100 column chromatography. The purified enzyme appeared homogeneous on electrophoresis and ultracentrifugation, and had a molecular weight of about 21, 000. This enzyme lysed viable yeast cells in the absence of any other enzymes or additives and was tentatively named zymolyase.
The optimum pH for lysis of viable yeast cells was 7.0-7.5, the optimum temperature was 35°, and the enzyme was relatively stable at pH 5-11. About 70% of its activity was lost on incubation at 50° for 5min, and all its activity was lost on incubation at 60° for 5min.
Studies on the hydrolyses of β-1, 3-glucans, i.e., yeast glucan, pachyman, curdlan, laminarin, and laminaran, showed that zymolyase is an endo-β-1, 3-glucanase, which specifically releases laminaripentaose as the minimum product unit. However, it behaves like an exo-enzyme in hydrolysis of high molecular β-1, 3-glucan, which shows strong molecular aggregation like yeast glucan, releasing laminaripentaose units. Zymolyase shows much more affinity for insoluble glucan than for soluble glucan.
