Draw Peptide Tool
Use the «Amino Acid Keypad» to build your desired peptide sequence by clicking on the amino acid buttons. As you input the sequence, the peptide's properties will be automatically calculated and displayed.
The sequence you create will appear in the text field below (Peptide Sequence). This field is for display only and does not require manual input. Once your sequence is complete, click the «Draw Peptide» button. It may take up to 5 seconds for the peptide image to generate.
| Peptide properties | |
|---|---|
| Sequence: | |
| Length: | |
| Mass: | |
| Isoelectric point (pI): | |
| Net charge: | |
| Hydrophobicity: | |
| Extinction coefficient1: | |
| Extinction coefficient2: |
Peptide Structure
If you need to save the peptide image, right-click on it and select "Save image as..." from the menu.
Peptide Properties Explained
Sequence: The peptide sequence you entered, displayed using the standard one-letter amino acid code.
Sequence Length: The total number of amino acids in your sequence. Only valid amino acid characters are counted.
Mass: The molecular weight of the peptide, calculated by summing the atomic masses of all its amino acid residues, including their side chains and the added mass of a water molecule.
Isoelectric Point (pI): The pH at which the peptide has no overall charge. This is determined by simulating charge changes at different pH levels, increasing in steps of 0.01.
Net Charge: The total electrical charge of the peptide at neutral pH, based on the balance of positively (basic) and negatively (acidic) charged amino acids.
Hydrophobicity (Wimley-White Scale): A measure of how the peptide interacts with water. This value represents the energy required to move the peptide from a water-based environment to a hydrophobic (oil-like) one, using the experimentally derived Wimley-White scale. The result is given in kcal/mol, assuming a neutral pH.
Molar Extinction Coefficient: A measure of how much light the peptide absorbs at 280 nm (UV light). The calculation is based on the number of tryptophan (W), tyrosine (Y), and cystine (disulfide-bonded cysteine) residues in the sequence.
Oxidized form (disulfide bonds present):
Extinction coefficient = (W × 5500) + (Y × 1490) + (Cystines × 125)
Reduced form (all cysteines are free):
Extinction coefficient = (W × 5500) + (Y × 1490)
The extinction coefficient helps estimate protein concentration in a sample by measuring UV absorption.