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Calf thymus alkaline phosphatase. II. Interaction with detergents
Biochimica Et Biophysica Acta
|January 11, 1977
Summary
Detergents affect alkaline phosphatase activity and stability by binding to the enzyme, altering its size, catalytic function, and heat sensitivity. Different detergents have varying impacts on enzyme properties.
Area of Science:
- Biochemistry
- Enzymology
- Membrane Biology
Background:
- Alkaline phosphatase is a key enzyme found in plasma membranes.
- Understanding how detergents interact with membrane-bound enzymes is crucial for biochemical studies.
Purpose of the Study:
- To investigate the effects of various detergents on the solubilization, activity, and stability of calf thymus alkaline phosphatase.
- To determine how detergent-enzyme interactions influence enzyme properties such as size, catalytic efficiency, and heat lability.
Main Methods:
- Solubilization of membrane-bound alkaline phosphatase using different detergents.
- Measurement of enzyme Stokes' radius by gel filtration.
- Assay of alkaline phosphatase catalytic activity (Vmax and Km).
- Assessment of enzyme heat stability (half-life at 55°C).
Main Results:
- Detergent choice significantly impacted alkaline phosphatase size, activity, and stability.
- Non-ionic detergents generally preserved or enhanced activity, while bile salts inhibited it.
- Alkyl sulfates increased enzyme lability to heat denaturation.
- Reactivation of inhibited enzyme was observed with specific lipids.
Conclusions:
- Detergents bind to solubilized alkaline phosphatase, influencing its conformation, size, and function.
- The nature of detergent-enzyme interaction dictates changes in catalytic activity and thermal stability.
- Lipid moieties play a role in modulating enzyme activity, as shown by reactivation experiments.