THE PLASMA-MEMBRANE ATPASE OF KLOECKERA-APICULATA - PURIFICATION, CHARACTERIZATION AND EFFECT OF ETHANOL ON ACTIVITY

Partially (6-fold) purified plasma membrane ATPase from an ethanol-sen sitive yeast, Kloeckera apiculata, had an optimum pH of 6.0, an optimu m temperature of 35 degrees C, a K-m of 3.6 mM ATP and a V-max of 11 m u mol P-i/min.mg protein. SDS-PAGE of the semi-purified plasma membran e showed a major band of 106 kDa. No in vivo activation of the ATPase by glucose was observed. Although 4% (v/v) ethanol decreased the growt h rate by 50% it did not affect the ATPase. Concentrations of ethanol greater than or equal to 2% (v/v) did, however, inhibit the enzyme in vitro. The characteristics of the enzyme did not change during growth in the presence of ethanol.