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Improved insulin stability through amino acid substitution.
D N Brems1, P L Brown, C Bryant
1Parenteral Products Research and Development, Eli Lilly & Co., Indianapolis, IN 46285.
Protein Engineering
|September 1, 1992
Summary
Insulin analog stability is linked to its structure. Maintaining insulin's native state protects disulfide bonds, crucial for chemical stability and preventing degradation during storage.
Area of Science:
- Biochemistry
- Pharmaceutical Sciences
- Protein Chemistry
Background:
- Insulin analogs are engineered for improved pharmacokinetics, but their chemical stability can be affected.
- Understanding stability is crucial for developing effective and safe insulin therapies.
Purpose of the Study:
- To investigate the relationship between structural modifications in insulin analogs and their chemical stability.
- To determine how amino acid substitutions impact the stability of insulin's disulfide bonds.
Main Methods:
- Assessed chemical stability of over 20 insulin analogs under accelerated storage conditions.
- Evaluated intramolecular conformational equilibria using equilibrium denaturation.
- Correlated Gibbs free energy of unfolding with chemical stability data.
Main Results:
- Specific substitutions (e.g., HB10 to aspartic acid) enhanced stability, while others (B28/B29) had variable effects.
- Disulfide-linked multimers formed via disulfide interchange were the primary degradation products.
- A strong positive correlation (R²=0.8) was found between conformational and chemical stability.
Conclusions:
- The chemical stability of insulin analogs' disulfides is thermodynamically controlled by their conformational equilibria.
- Maintaining the native state of insulin is vital for disulfide bond integrity and preventing degradation.