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Enzyme changes associated with mitoichondrial malic enzyme deficiency in mice
Biochimica Et Biophysica Acta
|October 18, 1979
Summary
Mice lacking mitochondrial malic enzyme show increased liver enzyme activity, particularly glucose-6-phosphate dehydrogenase. These changes, starting at 19 days, indicate increased enzyme protein, not a simple hormonal effect.
Area of Science:
- Biochemistry
- Genetics
- Metabolic pathways
Background:
- Mitochondrial malic enzyme (EC 1.1.1.40) plays a role in cellular metabolism.
- Genetic deficiencies can lead to compensatory metabolic adjustments.
Purpose of the Study:
- To investigate the metabolic consequences of a genetic absence of mitochondrial malic enzyme in mice.
- To characterize alterations in related enzyme activities in deficient mice.
Main Methods:
- Comparative analysis of enzyme activities in liver, heart, and kidney tissues of mutant and wild-type mice.
- Utilizing immunoinactivation assays with specific antisera to quantify enzyme protein levels.
Main Results:
- Mice lacking mitochondrial malic enzyme exhibited a four-fold increase in liver glucose-6-phosphate dehydrogenase and a two-fold increase in 6-phosphogluconate dehydrogenase.
- Unexpectedly, total malic enzyme activity in the liver increased by approximately 50% in deficient mice.
- Enzyme activity alterations began around 19-21 days of age and represented increased enzyme protein amounts.
Conclusions:
- The absence of mitochondrial malic enzyme triggers significant compensatory changes in liver carbohydrate metabolism.
- Increased enzyme protein levels suggest a complex regulatory response beyond simple hormonal signaling.