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Development of cholinephosphotransferase in guinea pig lung mitochondria and microsomes
Abstract:
Development of mitochondrial and microsomal choline phosphotransferase in the fetal guinea pig lung was investigated. The activity in fetal mitochondria was more than twice of that in fetal microsomes. However, in adult lung, the enzyme was distributed mostly in microsomes. In fetal lung, both the mitochondrial and microsomal enzyme activity was greatest at approx. 81% of the total gestation period (55 days). The specific activity in the microsomal fraction than declined until term, but increased again in the 24-h newborn from 1.0 to 2.3 nmol/min per mg protein. The activity in the mitochondrial fraction declined after 61 days (2.8 nmol/min per mg) to a minimal level at term (0.6 nmol/min per mg). Although the enzyme activity decreased from day 55 (1.2 nmol/min per mg), the amount of phosphatidylcholine gradually increased between day 55 and term.
Insights
Mitochondrial and microsomal choline phosphotransferase activity in fetal guinea pig lungs peaks mid-gestation. Postnatally, microsomal activity increases, while mitochondrial activity declines, impacting phosphatidylcholine levels.
Area of Science:
- Biochemistry
- Developmental Biology
- Pulmonary Medicine
Background:
- Choline phosphotransferase is crucial for phosphatidylcholine synthesis.
- Lung development involves dynamic changes in enzyme activity and localization.
Purpose of the Study:
- To investigate the developmental changes in mitochondrial and microsomal choline phosphotransferase activity in fetal guinea pig lungs.
- To correlate enzyme activity with phosphatidylcholine levels during lung development.
Main Methods:
- Enzyme activity assays were performed on mitochondrial and microsomal fractions from fetal and newborn guinea pig lungs.
- Specific activity was measured at various stages of gestation and postnatally.
Main Results:
- Fetal lung mitochondria showed higher choline phosphotransferase activity than microsomes.
- Peak enzyme activity in both fractions occurred around 81% of gestation (55 days).
- Microsomal activity increased significantly in newborns, while mitochondrial activity decreased towards term.
Conclusions:
- Choline phosphotransferase exhibits distinct developmental patterns in fetal guinea pig lung mitochondria and microsomes.
- These changes in enzyme activity likely contribute to the observed increase in phosphatidylcholine during late gestation and early postnatal life.