Enzymatic Regulation in the Liver of the Freeze-Tolerant Wood Frog in Metabolically Depressed States

The wood frog, Rana sylvatica, can tolerate high degrees of freeze-tolerance, a stress that also requires anoxia, dehydration and hyperglycemia tolerance. Frozen wood frogs show no heartbeat, brain activity, muscle movement or breathing, but phenomenally return to normal once thawed. Control of enzymatic activity is crucial for regulating metabolism and it is imperative for wood frog survival. This thesis investigates the properties of two key enzymes metabolic enzymes, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase in liver of the wood frogs exposed to freezing, dehydration and anoxia. Current data show that changes in activity, substrate affinity and stability of the enzymes play a major role in their regulation to support the survival of the wood frog during stress, and these regulations are partly controlled by post-translational modifications. Therefore, these enzymes undergo regulation at the level of posttranslational modification to contribute to the overall readjustment of energy production in the wood frog.