Protective role of trehalose in thermal denaturation of yeast pyrophosphatase

Trehalose, a disaccharide of glucose, is accumulated in yeast cytosol when this organism is submitted to a stress condition. Recently it was shown that the level of trehalose increase up to 15 times when yeast cells are submitted to heat shock (De Virgilio et al., 1991). In this report we give evidence how trehalose may play an important role on the stress-survival of yeasts when submitted to a heat shock. We show that 1.5 M trehalose increases 13-fold the half-time for thermal inactivation (t0.5) of yeast cytosolic pyrophosphatase at 50 degrees C. This thermal protection conferred by trehalose is dose-dependent, after 10 min at 50 degrees C, a condition which inactivated pyrophosphatase, the presence of 2 M trehalose preserves 95% of total activity. Other carbohydrates were tested but were not so effective as trehalose. The presence of trehalose at high concentrations in the reaction medium at 35 degrees C inhibits pyrophosphatase activity. This inhibition is less effective at 50 degrees C suggesting that under this condition the enzyme is temperature-protected and active.