Peptide Stability Estimator
Estimate peptide stability and shelf life from sequence features. Free online tool for researchers.
How to Use This Estimator
- Enter the sequence length (number of amino acid residues)
- Count and enter the number of degradation-prone residues (Asp, Asn, Met, Gln, Cys)
- Select any terminal modifications (acetylation, amidation)
- Indicate if the peptide is cyclized or contains D-amino acids
- Click Estimate to receive a predicted stability category
Degradation-Prone Amino Acids
| Residue | Degradation Pathway | Rate at pH 7.4, 37°C | Prevention |
|---|---|---|---|
| Asn (N) | Deamidation → Asp/isoAsp | t₁/₂ = 1–10 days | Gly substitution, low pH storage |
| Asp (D) | Isomerization → isoAsp | t₁/₂ = 5–20 days | Avoid Asp-Gly sequences |
| Met (M) | Oxidation → Met sulfoxide | t₁/₂ = hours–days | Inert atmosphere, antioxidants |
| Gln (Q) | Deamidation → Glu | t₁/₂ = 5–15 days | Low pH, low temperature |
| Cys (C) | Oxidation, disulfide scrambling | Variable | Alkylation, inert atmosphere |
Stability Classification
High Stability
Estimated plasma t₁/₂ > 12 hours. Suitable for once-daily or less frequent dosing. Few degradation-prone residues, protected termini.
Moderate Stability
Estimated plasma t₁/₂ 1–12 hours. Requires 2–4× daily dosing or depot formulation. Some degradation-prone residues present.
Low Stability
Estimated plasma t₁/₂ 15 min–1 hour. Requires continuous infusion or frequent dosing. Multiple degradation-prone residues.
Very Low Stability
Estimated plasma t₁/₂ < 15 minutes. Requires depot formulation, PEGylation, or D-amino acid substitution for therapeutic use.
Stabilization Strategies
| Strategy | Half-Life Extension | Mechanism |
|---|---|---|
| D-amino acid substitution | 3–10× increase | Resists protease degradation |
| Cyclization | 2–5× increase | Reduces exopeptidase access |
| N-terminal acetylation | 2–5× increase | Blocks aminopeptidases |
| C-terminal amidation | 2–3× increase | Blocks carboxypeptidases |
| PEGylation | 5–50× increase | Renal filtration resistance |
| Fatty acylation | 10–100× increase | Albumin binding, injection depot |
| Albumin fusion | 50–200× increase | Fc/albumin carrier protection |
Storage Recommendations
| Form | Temperature | Duration | Notes |
|---|---|---|---|
| Lyophilized | -20°C | 1–2 years | Most stable form; protect from light |
| Lyophilized | -80°C | 2–5 years | Long-term storage |
| Reconstituted | 4°C | 2–4 weeks | Sterile water or BAC water |
| Reconstituted | -20°C | 1–3 months | Aliquot to avoid freeze-thaw |
| Reconstituted | -80°C | 3–6 months | Single-use aliquots recommended |