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Product inhibition in native-state proteolysis.
Joseph R Kasper1, Elizabeth C Andrews1, Chiwook Park1
1Department of Medicinal Chemistry and Molecular Pharmacology, Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America.
Plos One
|November 1, 2014
Summary
Native-state proteolysis kinetics, used to study protein unfolding, deviates from first-order kinetics due to product inhibition. A new model accounts for this, enabling accurate assessment of protein energetics.
Area of Science:
- Biochemistry
- Protein Chemistry
- Enzymology
Background:
- Native-state proteolysis assesses protein energetics via kinetics of partial unfolding.
- First-order kinetics has been the standard assumption for analyzing native-state proteolysis.
- Understanding protein unfolding dynamics is crucial in biochemistry.
Purpose of the Study:
- To investigate deviations from first-order kinetics in native-state proteolysis.
- To identify the cause of kinetic deviations in proteolysis of intact proteins.
- To develop a kinetic model that accurately describes native-state proteolysis.
Main Methods:
- Incubation of intact proteins with nonspecific proteases (thermolysin, subtilisin).
- Analysis of proteolysis kinetics at varying substrate concentrations and in the presence of cleavage products.
- Development and application of a kinetic model incorporating competitive product inhibition.
Main Results:
- Proteolysis kinetics of intact proteins by thermolysin and subtilisin deviate from first-order kinetics.
- Product inhibition was identified as the cause of these kinetic deviations.
- A competitive product inhibition model accurately describes the proteolysis time course.
Conclusions:
- First-order kinetics is an insufficient assumption for native-state proteolysis analysis.
- Product inhibition must be considered for accurate quantitative assessment of proteolysis kinetics.
- The developed kinetic model allows determination of uninhibited rate and inhibition constants.
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