Aliphatic Index Calculator
Calculate the aliphatic index of protein sequences. Upload a FASTA file or paste your protein sequences below to get the aliphatic index values.
Input (Protein sequences)
FASTA
Click to upload or drag and drop
FASTA file (.fasta, .fas, .fa, .txt)
Max size: 50MB
Output options
Aliphatic index
Numbers
About aliphatic index calculation
The aliphatic index indicates thermostability of globular proteins:
- • Formula: AI = X(Ala) + 2.9×X(Val) + 3.9×(X(Ile) + X(Leu))
- • X = mole percent of each aliphatic amino acid
- • Low (<70): Low thermostability
- • Moderate (70-100): Moderate thermostability
- • High (>100): High thermostability
- • Reference: Ikai (1980)