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Calculateur de masse moléculaire des protéines

Estimez la masse moléculaire d'une protéine à partir du nombre de résidus (moy. 110 Da/résidu).

Introduction

Protein Molecular Weight Calculator — Estimate protein MW from residue count (avg. 110 Da/residue). Enter Number of amino acid residues (estimate uses ~110 Da per residue) to get an instant, accurate result.

Formule

Estimate only: molecular weight ≈ (number of residues × 110) + 18 Da, using an approximate average residue mass of ~110 Da plus 18 Da for the terminal water molecule. The actual molecular weight depends on the amino-acid composition/sequence; sequence-based tools such as ExPASy ProtParam, or the mass listed in a UniProt entry, give more accurate values.

Étape par étape

  1. Enter the Number of amino acid residues (estimate uses ~110 Da per residue).
  2. Click Calculate to see your result instantly.

Exemple concret

Example: With Number of amino acid residues (estimate uses ~110 Da per residue) = 150, the Protein Molecular Weight Calculator gives Estimated Molecular Weight Da: 16518, Note: Estimate only: about 110 Da per residue plus 18 Da for the terminal water. The true molecular weight depends on the actual amino-acid composition/sequence; sequence-based tools (e.g. ExPASy ProtParam, or the mass listed in UniProt) give more accurate values..

Questions Fréquentes

Why is this only an estimate rather than an exact mass?
Individual amino acids range from about 75 Da (glycine) to 204 Da (tryptophan) as residues, so using a single average (~110 Da) per residue gives a quick, reasonably close estimate rather than the exact mass you'd get from the real amino-acid composition.
Why is 18 added at the end?
That accounts for the extra water molecule (H₂O, ~18 Da) present at the free N- and C-termini of the finished protein, which isn't lost the way it is at internal peptide bonds.
What inputs does the Protein Molecular Weight Calculator need?
You'll need to provide: Number of amino acid residues (estimate uses ~110 Da per residue). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Protein Molecular Weight Calculator?
The Protein Molecular Weight Calculator applies the formula exactly as calculated — Estimate only: molecular weight ≈ (number of residues × 110) + 18 Da, using an approximate average residue mass of ~110 Da plus 18 Da for the terminal water molecule. The actual molecular weight depends on the amino-acid composition/sequence; sequence-based tools such as ExPASy ProtParam, or the mass listed in a UniProt entry, give more accurate values. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Protein Molecular Weight Calculator free to use?
Yes, the Protein Molecular Weight Calculator is completely free, requires no signup, and runs instantly in your browser.

À propos de Calculateur de masse moléculaire des protéines

The Protein Molecular Weight Calculator uses a real, verifiable formula — Estimate only: molecular weight ≈ (number of residues × 110) + 18 Da, using an approximate average residue mass of ~110 Da plus 18 Da for the terminal water molecule. The actual molecular weight depends on the amino-acid composition/sequence; sequence-based tools such as ExPASy ProtParam, or the mass listed in a UniProt entry, give more accurate values. — so results are accurate every time, not an approximation.