Protein instability index calculator
Calculate the instability index of protein sequences. Upload a FASTA file or paste your protein sequences below to get the instability index values.
Input (Protein sequences or PDB structure)
Calculation options
Instability index
Instability index results will appear here automatically.
Enter a protein sequence above to begin.
About instability index calculation
The instability index predicts protein stability in a test tube:
- • Method: Based on dipeptide instability weights (DIWV)
- • Formula: II = (10/L) × Σ DIWV(AiAi+1)
- • Stable: II < 40 (stable in vitro)
- • Unstable: II ≥ 40 (unstable in vitro)
- • Reference: Guruprasad et al. (1990)
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