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Phosphatidate phosphohydrolase in purified rat brain myelin
1Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York.
Journal of Neuroscience Research
|November 1, 1989
Summary
Myelin in rat brain stems contains phosphatidate phosphohydrolase, an enzyme crucial for lipid synthesis. This finding suggests the enzyme is integral to the myelin membrane, not a contaminant.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Myelin, the insulating sheath around nerve fibers, plays a critical role in neural function.
- Subcellular localization of enzymes provides insights into cellular metabolic pathways.
- Phosphatidate phosphohydrolase is a key enzyme in glycerolipid synthesis.
Purpose of the Study:
- To determine the presence and localization of phosphatidate phosphohydrolase within purified rat brain stem myelin.
- To investigate whether phosphatidate phosphohydrolase activity in myelin is due to intrinsic enzyme or contamination.
Main Methods:
- Enzyme assays on highly purified rat brain stem myelin.
- Comparison of enzyme activity in myelin versus cytosol and microsomal fractions.
- Analysis of enzyme activity after repeated purification, mixing experiments, and salt/detergent washes.
Main Results:
- Phosphatidate phosphohydrolase was detected in highly purified rat brain stem myelin.
- Enzyme levels in myelin were significant relative to cytosol and microsomes.
- Purification and washing experiments supported the enzyme's intrinsic presence in myelin.
Conclusions:
- Phosphatidate phosphohydrolase is an intrinsic component of the myelin membrane.
- This enzyme generates diacylglycerol, a substrate for the cytidine (Kennedy) pathway in myelin.
- The findings elucidate a novel metabolic function within the myelin sheath.