Sola-Penna M, Meyer-Fernades J R
Departamento de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Brasil.
Z Naturforsch C J Biosci. 1994 May-Jun;49(5-6):327-30. doi: 10.1515/znc-1994-5-608.
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.
海藻糖是一种葡萄糖二糖，当酵母处于应激状态时会在其细胞质中积累。最近有研究表明，当酵母细胞受到热休克时，海藻糖水平会增加至15倍（德·维尔吉利奥等人，1991年）。在本报告中，我们提供了证据，证明海藻糖在酵母受到热休克时的应激存活中可能发挥重要作用。我们发现，1.5M海藻糖可使酵母细胞质焦磷酸酶在50℃下热失活的半衰期（t0.5）延长13倍。海藻糖提供的这种热保护作用具有剂量依赖性，在50℃下10分钟后，焦磷酸酶会失活，而2M海藻糖的存在可保留95%的总活性。我们还测试了其他碳水化合物，但它们的效果不如海藻糖。在35℃的反应介质中，高浓度的海藻糖会抑制焦磷酸酶的活性。这种抑制在50℃时效果较差，这表明在这种条件下该酶受到温度保护且具有活性。
