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Hydroxylating activity of frog epidermis tyrosinase
Revista Espanola De Fisiologia
|June 1, 1979
Summary
Frog epidermis tyrosinase activation by trypsin affects both tyrosine hydroxylase and dopa-oxidase activities. Enzyme inactivation during activation suggests a spatial unfolding mechanism for tyrosinase.
Area of Science:
- Biochemistry
- Enzymology
- Dermatology
Background:
- Frog epidermis tyrosinase exhibits complex activation kinetics.
- Understanding tyrosinase activation is crucial for its biological roles.
Purpose of the Study:
- To investigate the activation mechanism of frog epidermis tyrosinase.
- To characterize the tyrosine hydroxylase and dopa-oxidase activities.
Main Methods:
- Enzyme kinetics assays using tyrosine and dopa.
- Investigated the effect of trypsin and electron donors on enzyme activity.
- Analyzed thermal denaturation profiles.
Main Results:
- Trypsin activated both tyrosine hydroxylase and dopa-oxidase activities.
- Electron donors reduced the lag period for hydroxylating enzyme.
- Dopa acted as a competitive inhibitor for tyrosine hydroxylase.
- Enzyme inactivation observed during activation, with thermal denaturation data similar to dopa oxidase.
Conclusions:
- Activation of frog epidermis tyrosinase involves enzyme inactivation.
- Results support the hypothesis of enzyme molecule spatial unfolding during activation.