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Desialylated alkaline phosphatase: activation by 4-nitrophenol
Biochemistry International
|January 1, 1984
Summary
Mouse ileal alkaline phosphatase activity is reduced by sialic acid removal but partially recovered through product binding. This suggests conformational changes in the enzyme influence its function.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Mouse ileal alkaline phosphatase is a sialyl enzyme.
- Sialylation plays a role in enzyme activity and stability.
Purpose of the Study:
- To investigate the effect of partial desialylation on mouse ileal alkaline phosphatase activity.
- To explore the mechanism of activity recovery upon product accumulation.
Main Methods:
- Enzyme activity assays.
- Neuraminidase treatment to partially desialylate the enzyme.
- Analysis of kinetic parameters (Vmax and Km).
Main Results:
- Partial desialylation significantly reduced enzyme activity, Vmax, and Km.
- Enzyme activity was partially recovered as 4-nitrophenol concentration increased.
- Ligand binding of 4-nitrophenol to the desialylated enzyme was demonstrated.
- Changes in protein conformation correlated with both activity loss and ligand-induced activation.
Conclusions:
- Sialic acid residues are crucial for maintaining the full activity of mouse ileal alkaline phosphatase.
- The enzyme's conformation is altered by desialylation and ligand binding, affecting its catalytic efficiency.