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Conformational impurity of disulfide proteins: detection, quantification, and properties
Jui-Yoa Chang1, Bao-Yuan Lu, Li Li
1Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas, Houston, TX 77030, USA. rowen.chang@uth.tmc.edu
Analytical Biochemistry
|June 17, 2005
Summary
Native proteins exist in equilibrium with small amounts of nonnative isomers, which can aggregate and cause neurodegenerative diseases. A new disulfide scrambling technique can now detect and quantify these elusive protein conformations.
Area of Science:
- Biochemistry
- Protein dynamics
- Neurodegenerative disease research
Background:
- Protein structure is primarily governed by thermodynamics, leading to an equilibrium between native and nonnative (denatured) states.
- Even under physiological conditions, a small fraction of nonnative protein isomers exist.
- These nonnative isomers are implicated in protein aggregation and are a key factor in neurodegenerative diseases.
Purpose of the Study:
- To develop a method for detecting and quantifying minute concentrations of nonnative protein isomers.
- To investigate the prevalence of nonnative isomers in stable proteins under physiological conditions.
Main Methods:
- Utilizing disulfide scrambling technique.
- Applying the method to small, stable proteins like epidermal growth factor and hirudin.
Main Results:
- The study successfully identified and quantified nonnative protein isomers.
- Approximately 1% of nonnative isomers were found to coexist with native proteins.
Conclusions:
- The disulfide scrambling technique provides a viable strategy for detecting and quantifying nonnative protein isomers.
- The presence of nonnative isomers, even at low concentrations, is a common characteristic of proteins under physiological conditions.
- This finding has implications for understanding the molecular mechanisms of neurodegenerative diseases.