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Pyrophosphate-dependent phosphofructokinase from Giardia lamblia: purification and characterization
1Department of Medicine and Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106-4983, USA.
Protein Expression and Purification
|June 1, 1995
Summary
The pyrophosphate-dependent phosphofructokinase from Giardia lamblia was purified and characterized. Its unique properties, including neutral pH optima and distinct molecular weight, differentiate it from other known enzymes.
Area of Science:
- Biochemistry
- Enzymology
- Parasitology
Background:
- Phosphofructokinase (PFK) is a key glycolytic enzyme.
- Pyrophosphate-dependent PFK (PPi-PFK) is found in various anaerobic organisms.
- Giardia lamblia possesses a unique PPi-PFK.
Purpose of the Study:
- To purify and characterize the PPi-PFK from Giardia lamblia.
- To compare its properties with other known PPi-PFKs.
Main Methods:
- Enzyme purification using two distinct methods.
- Homogeneity assessment via SDS-PAGE and reverse-phase HPLC.
- Molecular weight determination using SDS-PAGE, native PAGE, and HPLC gel filtration.
- Kinetic analysis including pH optima and Michaelis-Menten kinetics.
Main Results:
- The purified Giardia lamblia PPi-PFK is a homogeneous monomeric protein of approximately 64 kDa.
- The enzyme exhibits neutral pH optima for both glycolytic and gluconeogenic reactions, differing from other PPi-PFKs.
- Kinetic analysis revealed Michaelis-Menten behavior with specific Km values for pyrophosphate and fructose 6-phosphate.
- Nucleoside triphosphates cannot substitute for pyrophosphate, and fructose 2,6-bisphosphate acts as a competitive inhibitor in the reverse reaction.
Conclusions:
- The Giardia lamblia PPi-PFK possesses unique biochemical and molecular properties.
- These distinct characteristics differentiate it from the two known classes of pyrophosphate-dependent phosphofructokinases.
- The findings contribute to understanding metabolic diversity in parasitic protozoa.
