Related Experiment Videos
Methylating activity in ovarian membranes changes during the estrous cycle
L B Oliveros1, M Carrasco, L I Aguado
1Laboratory of Biology of the Reproduction, Faculty of Chemistry, Biochemistry and Pharmacy, National University of San Luis, Argentina.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|May 1, 1997
Summary
This study characterized ovarian membrane methylation systems, identifying two key enzymes (Met I and Met II) involved in phospholipid metabolism. Their activity is hormonally regulated during the estrous cycle, suggesting a role in ovarian physiology.
Area of Science:
- Biochemistry
- Reproductive Biology
- Cellular Physiology
Background:
- Phosphatidylethanolamine (PE) methylation is crucial for cell membrane function.
- The ovarian physiology is intricately regulated by hormonal fluctuations during the estrous cycle.
- Understanding enzymatic pathways in ovarian membranes provides insights into reproductive health.
Purpose of the Study:
- To characterize the phosphatidylethanolamine (PE) methylation system in ovarian membranes.
- To identify the specific roles of identified methylating enzymes (Met I and Met II) in ovarian physiology.
- To investigate the influence of the hormonal environment during the estrous cycle on ovarian methylation activity.
Main Methods:
- Utilized S-adenosyl-L-[methyl-3H] methionine (SAM) as a methyl donor to identify and characterize methylating activities.
- Assessed kinetic properties (Km, Vm) and optimal pH for Met I and Met II.
- Measured methylating activity in ovarian membranes across different stages of the estrous cycle and after pregnant mare serum gonadotrophin (PMSG) administration.
Main Results:
- Identified two distinct methylating activities: Met I (PE to PME) and Met II (PME to PC).
- Met I exhibited optimal activity at pH 6.5 (Km 5.71 µM, Vm 1.53 pmol/mg/min), while Met II showed optimal activity at pH 9.5 (Km 50 µM, Vm 1.2 pmol/mg/min).
- Both activities were induced during proestrus, with Met I also induced during diestrus. PMSG injection increased total methylating activity.
Conclusions:
- Ovarian membranes possess a distinct phospholipid methylation system involving Met I and Met II.
- The activity of these enzymes is modulated by the hormonal milieu of the estrous cycle.
- Phospholipid methylation likely plays a regulated role in ovarian physiology, influenced by hormonal cues.