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Phosphofructokinase of calf trabecular meshwork.
Investigative Ophthalmology & Visual Science
|November 1, 1984
Summary
Ammonium (NH4+) is essential for phosphofructokinase (PFK) activity in trabecular meshwork, suggesting a key role in regulating glycolysis. This enzyme
Area of Science:
- Biochemistry
- Ocular Physiology
Background:
- Phosphofructokinase (PFK) is a critical enzyme regulating glycolysis.
- The trabecular meshwork is vital for maintaining intraocular pressure.
Purpose of the Study:
- To investigate the activity and regulatory properties of PFK in calf trabecular meshwork.
- To determine the role of ammonium (NH4+) in PFK function within this tissue.
Main Methods:
- Enzyme activity assays of PFK were performed on homogenates of calf trabecular meshwork.
- Varying concentrations of substrates and cofactors (NH4+, AMP, ATP) were tested at different pH levels (7.2 and 8.5).
Main Results:
- PFK activity was highly dependent on the presence of NH4+ at both tested pH values.
- AMP and ATP modulated PFK activity, with effects significantly influenced by pH.
- Optimal PFK activity required substantial NH4+ concentrations (10-30 mM), with lower levels showing partial activation.
Conclusions:
- NH4+ is a critical cofactor for PFK in the trabecular meshwork, independent of pH.
- These findings suggest a significant regulatory role for ammonium in controlling glycolysis within the trabecular meshwork.
- The physiological concentration of ammonium in aqueous humor supports its potential role in PFK regulation.