Peptide and protein
sequence tools
Explore how a sequence can describe molecular mass, amino acid composition, and charge.
Explore the sequence tools
Calculate molecular weight, amino acid composition, or theoretical isoelectric point, or review a sequence report.
- 01AvailableMass
Molecular Weight Calculator
Calculate average and monoisotopic peptide or protein mass in daltons from a sequence or single FASTA record.
- 02AvailableComposition
Amino Acid Composition Calculator
Count the 20 standard amino acids in a peptide or protein, compare percentages, and copy the sorted table as CSV or TSV.
- 03AvailableSequence
Peptide Sequence Analyzer
Analyze one peptide sequence for length, amino acid composition, and average and monoisotopic mass in a copyable report.
- 04AvailableCharge
Isoelectric Point Calculator
Estimate theoretical peptide or protein isoelectric point (pI) from sequence using a versioned Bjellqvist pKa model.
- 05AvailableAbsorbance
Extinction Coefficient Calculator
Estimate a protein’s theoretical molar extinction coefficient at 280 nm from tryptophan, tyrosine, and cystine.
- 06AvailableCharge
Net Charge Calculator
Plot theoretical peptide or protein net charge from pH 0 to 14 using the Bjellqvist pKa model. Read the values or copy the full curve as TSV.
- 07AvailableHydropathy
Hydropathy Calculator
Calculate mean Kyte–Doolittle hydropathy and plot a peptide or protein profile with a custom sliding window.
- 08AvailableSequence
Protein FASTA Validator
Validate multiple protein FASTA records, locate errors by line and column, and format valid sequences without changing residue order.
- 09AvailableSequence
Amino Acid Code Converter
Convert standard amino acid codes between one-letter and three-letter notation and identify ambiguous or unknown codes.