FORMATION AND CHARACTERIZATION OF THREE TYPES OF YEAST INVERTASE

摘要

Three types of invertase (invertase I, II and III) are separated from the soluble and insoluble fractions (4,500×g, 10 min supernatant and pellets of the homogenate, respectively) of baker's yeast by a DEAE cellulose column chromatography. The invertases I and II are eluted with 0.1msodium acetate buffer (pH 3.9) and with 0.1 M sodium acetate buffer (pH 6.2) containing 0.1 M NaCl from DEAE cellulose respectively, whereas the invertase-III remains adsorbed on the cellulose under these conditions. They are present in proportions of 2.5: 1 : 0.06 in the soluble fraction and 1.4: 1 : 0.12 in the insoluble fraction of the fresh baker's yeast cells. While in-vertase-II remains at a constant level, invertases I and III in the soluble fraction increase upon incubation of cells for the formation of invertase under the continuous supply of sucrose.Invertases I and II differ from each other considerably in the optimum pH and slightly in the response to (activation and inactivation by) crude papain and are identical with respect to the heat stability and probably to the affinity for sucrose