What are Potential Causes of Polypeptide Instability?

Q: What are Potential Causes of Polypeptide Instability?

• Deamidation: non-enzymatic deamidation reactions related to environmental conditions and polypeptide structure • Oxidized: Peroxide contamination, or spontaneous oxidation, with Met, Cys, His, Trp, Tyr being the most susceptible. Oxygen partial pressure, temperature, and buffer solution also affect oxidation. • Hydrolysis: Peptide bonds are susceptible to hydrolytic cleavage. Peptide bonds involving Asp are more prone to cleavage, especially Asp-Pro and Asp-Gly peptide bonds • Disulfide bond mismatch • Racemization: All amino acid residues except Gly have chiral carbon atoms and are susceptible to racemization, especially under alkaline conditions. (Asp residues are more easily eliminated). • β-elimination: β-elimination refers to the elimination of groups on the β carbon atom of residue amino acid residues. Residues such as Cys, Ser, Thr and Phe can undergo β-elimination, particularly at alkaline pH. • Denaturation, adsorption, aggregation or precipitation: Peptides such as IL-13, IL-2 and certain skin peptides are prone to adsorption.

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Accepted Answer

• Deamidation: non-enzymatic deamidation reactions related to environmental conditions and polypeptide structure

• Oxidized: Peroxide contamination, or spontaneous oxidation, with Met, Cys, His, Trp, Tyr being the most susceptible. Oxygen partial pressure, temperature, and buffer solution also affect oxidation.

• Hydrolysis: Peptide bonds are susceptible to hydrolytic cleavage. Peptide bonds involving Asp are more prone to cleavage, especially Asp-Pro and Asp-Gly peptide bonds

• Disulfide bond mismatch

• Racemization: All amino acid residues except Gly have chiral carbon atoms and are susceptible to racemization, especially under alkaline conditions. (Asp residues are more easily eliminated).

• β-elimination: β-elimination refers to the elimination of groups on the β carbon atom of residue amino acid residues. Residues such as Cys, Ser, Thr and Phe can undergo β-elimination, particularly at alkaline pH.

• Denaturation, adsorption, aggregation or precipitation: Peptides such as IL-13, IL-2 and certain skin peptides are prone to adsorption.