Secretory character of yeast chitinase.

During the conversion of yeast cells to protoplasts, about half of the yeast chitinase was liberated into the medium, an indication that this portion of the enzyme is located in the periplasmic space. At least part of the remaining chitinase appears to be enclosed in vacuoles or in vesicle that co-purify with them, as indicated by a 14-fold enrichment of the enzymatic activity in a vacuole fraction isolated from a protoplast lysate. When protoplasts were incubated in growth medium, part of the chitinase was liberated in growth medium, part of the chitinase was liberated into the medium. It is concluded that yeast chitinase is a secretory enzyme, like invertase and acid phosphatase. The enzyme appears to be stored in vesicles as a prelude to its secretion into the periplasmic space. The possible function of yeast chitinase in cell division is discussed.