Peso molecular proteína
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
AA × 110 - 18n
About this calculator
The Protein Molecular Weight calculator estimates a protein's molecular mass based on the number of amino acids and a simplified formula. Each amino acid contributes approximately 110 daltons (Da) to the total weight, while peptide bonds formed release water molecules (18 Da each). The formula PM ≈ (AA × 110) - 18n accounts for the total amino acids (AA) and peptide bonds (n-1).
This tool is useful in biological research, such as protein sequence analysis, drug development, or genetic studies. The 110 Da average per amino acid and 18 Da per bond are simplified approximations, valid for common proteins. Proteins with post-translational modifications (e.g., glycosylation) may require more precise calculations.
Common precautions include: verifying the amino acid sequence accuracy, noting that the formula ignores chemical modifications, and checking if the approximation suits the research context. For rigorous scientific calculations, specialized tools like sequence-based molecular weight calculators are recommended.
Frequently asked questions
Why subtract 18n in the formula?
Each peptide bond between amino acids releases a water molecule (18 Da). The formula accounts for the total amino acids (n) and subtracts the mass of water lost during bond formation.
Is the 110 Da per amino acid approximation accurate?
No. The 110 Da average is a simplification. Actual amino acid masses vary (e.g., glycine is 75 Da, tryptophan is 204 Da). The formula works for quick estimates, not detailed analysis.
When to use this calculator instead of specialized tools?
Use it for quick estimates in school projects or low-complexity experiments. For formal scientific studies, use software that calculates molecular weight from exact amino acid sequences.
Do chemical modifications affect the calculation?
Yes. The formula ignores modifications like phosphorylation or glycosylation, which change molecular mass. For modified proteins, use tools that include these factors.