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Peptide and Protein Molecular Weight Calculator
The molecular weight (mw) of an oligopeptide or a protein can be determined by summation of the mw of its corresponding amino acid sequence. Certain modifications to this sequences can result in changes to the mw. This calculator provides the mw of an unmodified oligopeptide or protein.
The extinction coefficient of a oligopeptide or protein can also be calculated given its sequence. This value is useful for determining the concentration of a peptide or protein solution.
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References
This online resource may be cited as follows
MLA
"Quest Calculate™ Peptide and Protein Molecular Weight Calculator." AAT Bioquest, Inc., 13 Sep. 2026, https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.
APA
AAT Bioquest, Inc. (2026, September 13). Quest Calculate™ Peptide and Protein Molecular Weight Calculator. AAT Bioquest. https://www.aatbio.com/tools/calculate-peptide-and-protein-molecular-weight-mw.
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This online resource has been cited in 14 publications, including
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The FASEB Journal (2026): e72266
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Scientific Reports (2025): 40969
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PLOS Computational Biology (2025): e1013422
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Heterologous expression, characterization, and application of recombinant thermostable $\alpha$-amylase from Geobacillus sp. DS3 for porous starch production
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Biochemistry and Biophysics Reports (2024): 101784
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Toxins (2024): 101
Unveiling the Relationship between Ceftobiprole and High-Molecular-Mass (HMM) Penicillin-Binding Proteins (PBPs) in Enterococcus faecalis
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Current Genetics (2022): 1--19
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Jang, Hyesun and Ross, Ted M
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PloS one (2021): e0246613
Design and Expression of VP1 (O IR/P50/2016) Protein in a Prokaryotic System as a Vaccine Candidate against Foot and Mouth Disease
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Vaccine Research : 44--48
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