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An activation factor of liver phosphofructokinase
Summary
A newly isolated factor prevents ATP inhibition of pure phosphofructokinase (PFK). This factor, along with AMP, regulates liver glycolysis, ensuring sufficient flux.
Area of Science:
- Biochemistry
- Enzymology
- Metabolic Regulation
Background:
- Pure liver phosphofructokinase (PFK) is strongly inhibited by ATP.
- Crude PFK exhibits only slight ATP inhibition, suggesting a regulatory factor is lost during purification.
Purpose of the Study:
- To isolate and characterize the factor preventing ATP inhibition of PFK.
- To elucidate the regulatory mechanism of PFK activity in liver glycolysis.
Main Methods:
- Enzyme purification and characterization.
- Gel filtration on Sephadex G-25 to resolve the activation factor.
- Assay of PFK activity under varying conditions with ATP, activation factor, and AMP.
Main Results:
- An activation factor, separable into three components by molecular weight, was isolated.
- This factor reverses ATP inhibition of PFK without affecting basal catalytic activity.
- AMP acts synergistically with the activation factor to overcome ATP inhibition.
Conclusions:
- The isolated activation factor and AMP are crucial for regulating PFK activity.
- This regulatory system adequately explains the glycolytic flux observed in liver tissue.