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Trypsin modification of phosphofructokinase from Ascaris suum
P A Ahanotu1, E Ahanotu, N G Srinivasan
1Department of Biochemistry and Molecular Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
Molecular and Biochemical Parasitology
|March 1, 1991
Summary
Ascaris suum phosphofructokinase, a key enzyme in glycolysis, retains catalytic activity after trypsin digestion, suggesting structural similarity to mammalian enzymes. This study investigates its enzymatic properties and structural integrity.
Area of Science:
- Biochemistry
- Enzymology
- Parasitology
Background:
- Phosphofructokinase (PFK) is a crucial enzyme in glycolysis.
- Understanding PFK structure and function is vital for metabolic studies.
- Ascaris suum PFK serves as a model for parasitic enzymes.
Purpose of the Study:
- To investigate the structural and functional consequences of trypsin digestion on Ascaris suum phosphofructokinase.
- To compare the properties of digested Ascaris suum PFK with its native form and mammalian PFK.
Main Methods:
- Enzyme purification and characterization.
- Limited proteolysis using trypsin.
- SDS-gel electrophoresis for fragment analysis.
- Gel filtration for molecular weight determination.
- Enzyme activity assays and kinetic analysis.
Main Results:
- Trypsin digestion generated 40, 37, and 32 kDa fragments with <50% loss of catalytic activity.
- Digested enzyme maintained its tetrameric structure and was less inhibited by ATP.
- Phosphorylated peptides were released upon digestion, but effector sensitivity (fructose 2,6-bisphosphate, AMP) remained.
- The structural integrity and partial activity suggest similarity to mammalian PFK.
Conclusions:
- Ascaris suum PFK exhibits remarkable structural stability upon limited proteolysis.
- The enzyme's active site or regulatory regions may be less susceptible to trypsin.
- Structural similarities between Ascaris suum and mammalian PFK support conserved functional domains.