抄録
Residual biological activity of lactate dehydrogenase (LDH) freeze-dried in present of four kinds of disaccharides (i.e. trehalose (TRE), sucrose (SUC), maltose (MAL) and lactose (LAC)) was examined, and the stabilizing effect of dissacharides was compared and discussed based on water replacement and glass transition hypothesis. Every disaccharide protected LDH from stress induced by freeze-drying, although the protecting ability was almost same degree among them. However, the more residual moisture content of sample raised the LDH residual activity. This result will be explained by steric hindrance of water replacement by dissacharide. Although LDH lost all of the activity within one month during storage at the temperature above T_g, when the sample was in glassy state at the same temperature, the activity was enough kept. This will result from the immobilizing effect by glass transition. On the other hand, when the sample was stored below the T_g, TRE and SUC enough protected LDH during at least three months. However, MAL and LAC destabilized LDH by the browning reaction to LDH. It is thought that TRE has non-reactivity to protein and high T_g will work to protein as the most effective lyoprotectant among four disaccharides through the current research.
