RELEASE OF ENZYMES FROM RAT LIVER MITOCHONDRIA BY FREEZING

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Abstract
Glutamate and 3-hydroxybutyrate dehydrogenase activities were used to estimate freezing damage to mitochondria.Freezing damage occurred in mitochondria by two steps: one was rapid and involved changes in membrane structure to expose 3-hydroxybutyrate dehydrogenase with concomitant release of glutamate dehydrogenase; the other was a slow extraction of glutamate dehydrogenase. The effect of freezing and thawing was very similar to the effect of exposure to high sucrose concentration and redilution. The data indicate that freezing temperature not only determined the sucrose concentration but also regulated the diffusion of sucrose. A combination of effects, of sucrose concentration and of diffusion, resulted in maximum damage at about −15 °C, while below −40 °C no damage was detectable.