Related Experiment Videos
Phosphofructokinase from mollusc muscle is activated by phosphorylation
M Biethinger1, R Hoffmann, H W Hofer
1Faculty of Biology, University of Konstanz, Germany.
Archives of Biochemistry and Biophysics
|June 1, 1991
Summary
This study purified phosphofructokinase from snail and mussel muscles, finding phosphorylation by protein kinase altered enzyme activity and substrate affinity. These findings offer insights into molluscan enzyme regulation.
Area of Science:
- Biochemistry
- Enzymology
- Comparative Physiology
Background:
- Phosphofructokinase (PFK) is a key glycolytic enzyme.
- Molluscan PFK regulation is less understood than in other organisms.
- Enzyme phosphorylation is a common regulatory mechanism.
Purpose of the Study:
- To purify and characterize phosphofructokinase from two distinct mollusc species: Helix pomatia (gastropod) and Mytilus edulis (bivalve).
- To investigate the effects of phosphorylation by cyclic AMP (cAMP)-dependent protein kinase on the kinetic properties of these enzymes.
Main Methods:
- Purification of phosphofructokinase from snail and mussel muscle tissues.
- In vitro phosphorylation assays using purified protein kinase catalytic subunits.
- Analysis of enzyme kinetics, including ATP inhibition, fructose 6-phosphate affinity, and Vmax.
Main Results:
- Both snail and mussel PFKs had a molecular mass of 82 kDa and were phosphorylated by cAMP-dependent protein kinase.
- Phosphorylation decreased ATP inhibition and increased fructose 6-phosphate affinity for both enzymes.
- Mussel PFK showed a marked increase in Vmax upon phosphorylation when activated by 5'-AMP or fructose 2,6-bisphosphate.
Conclusions:
- Phosphorylation significantly modulates the activity and substrate binding of molluscan phosphofructokinases.
- The regulatory mechanisms of PFK in gastropods and bivalves share similarities but also exhibit species-specific differences.
- These findings contribute to understanding metabolic regulation in invertebrates.