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A novel pathway to enzyme deactivation: the cutinase model
R P Baptista1, L Y Chen, A Paixão
1Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, Lisboa, Portugal.
Biotechnology and Bioengineering
|April 18, 2003
Summary
Cutinase enzyme deactivation involves a parallel pathway where unfolded proteins aggregate at high concentrations. A subsequent first-order process dominates as aggregates mature, indicating complex enzyme instability.
Area of Science:
- Biochemistry
- Enzymology
- Protein Chemistry
Background:
- Enzyme deactivation is crucial for understanding protein stability and function.
- Cutinase, an esterase, is susceptible to unfolding and aggregation under specific conditions.
- The deactivation mechanisms of enzymes can be complex, involving multiple parallel or sequential pathways.
Purpose of the Study:
- To elucidate the deactivation pathway of cutinase in aqueous solution at pH 4.5.
- To investigate the role of protein concentration and temperature on cutinase deactivation.
- To characterize the aggregation process and its impact on enzyme stability.
Main Methods:
- Enzyme kinetics assays to monitor deactivation.
- Dynamic light scattering to determine aggregate size.
- Analysis of reaction order to understand aggregation mechanisms.
Main Results:
- Cutinase deactivates via a parallel pathway at pH 4.5 and 53°C.
- At high protein concentrations (≥12 μM), unfolded cutinase aggregates with a reaction order of 3.
- Aggregates showed a sixfold increase in size, followed by a concentration-independent first-order deactivation phase.
Conclusions:
- Enzyme deactivation can involve kinetic partitioning between aggregation and irreversible conformational changes.
- Protein concentration significantly influences the initial aggregation phase of cutinase deactivation.
- Understanding these complex deactivation pathways is vital for enzyme applications and stability studies.