Mol Weight Calculator Protein

Protein Molecular Weight Formula:

\[ MW = \sum (AA Masses) - (n-1) \times 18.015 \]

Molecular Weight (MW):

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1. What Is Protein Molecular Weight?

Protein molecular weight is the sum of the masses of all atoms in a protein molecule, typically expressed in g/mol. It's calculated by summing the masses of individual amino acids and subtracting the mass of water molecules lost during peptide bond formation.

2. How Does The Calculator Work?

The calculator uses the formula:

\[ MW = \sum (AA Masses) - (n-1) \times 18.015 \]

Where:

\( \sum (AA Masses) \) — Sum of individual amino acid masses
\( n \) — Number of amino acids in the sequence
\( 18.015 \) — Molecular mass of water (g/mol)

Explanation: For each peptide bond formed during protein synthesis, one water molecule is removed, which must be accounted for in the molecular weight calculation.

3. Importance Of Molecular Weight Calculation

Details: Knowing a protein's molecular weight is essential for protein purification, electrophoresis, mass spectrometry, biochemical assays, and pharmaceutical development.

4. Using The Calculator

Tips: Enter the amino acid sequence using single-letter codes (e.g., "GAMMA"). The calculator automatically removes spaces and non-amino acid characters before calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why subtract water molecules?
A: During peptide bond formation, a condensation reaction occurs where water is removed. The molecular weight calculation accounts for this mass loss.

Q2: Are modified amino acids supported?
A: This calculator uses standard amino acid masses. For modified residues, specialized calculators or manual adjustment may be needed.

Q3: How accurate is this calculation?
A: The calculation provides a theoretical molecular weight. Actual experimental values may vary slightly due to isotopic distribution and post-translational modifications.

Q4: What about disulfide bonds?
A: Disulfide bond formation involves loss of hydrogen atoms (not full water molecules), which isn't accounted for in this basic calculation.

Q5: Can I calculate molecular weight with modifications?
A: For proteins with modifications (phosphorylation, glycosylation, etc.), you'll need to add the mass of the modification groups to the calculated result.