Protein Molecular Weight Calculator
Chemistry & BiologyCalculate the molecular weight of a 5-amino-acid peptide chain from its amino acid sequence.
Molecular Weight
Molecular weight of the 5-amino-acid peptide chain, in unified atomic mass units (u), after subtracting the water released at each of the 4 peptide bonds formed.
Molecular Weight (kDa)
0.3734
The same molecular weight expressed in kilodaltons.
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Odeh Ahwal0people find this calculator helpful
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Chemistry & Biology calculators
Frequently Asked Questions
Why is water subtracted for each peptide bond?
Forming a peptide bond between two amino acids releases one water molecule, in a reaction called condensation. Summing the free amino acid weights directly would overcount the total by one water molecule per bond formed, so each bond subtracts 18.0153 atomic mass units, the weight of water.
Why does this cover exactly 5 amino acids?
A protein or peptide can have any number of amino acids. This calculator fixes the chain at 5 positions to keep the tool simple and usable; the same water-subtraction principle applies to a chain of any length, just with more terms summed and one fewer water subtraction than the total amino acid count.
How does this compare to the general molar mass calculator?
The molar mass calculator works from a chemical formula built from individual elements. This calculator instead works from a sequence of amino acid building blocks, automatically accounting for the water lost at each peptide bond, which a generic molar mass formula would not do.
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