1. What is Protein Molar Mass?

Protein molar mass is the mass of one mole of a protein, typically expressed in grams per mole (g/mol). It's calculated by summing the molar masses of all amino acids in the protein sequence, accounting for water loss during peptide bond formation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( MW \) — Molar mass in grams per mole
• \( AA \) — Amino acid residues in the protein sequence
• The calculation includes the mass of water (18.02 g/mol) for terminal groups

Explanation: The calculator sums the molar masses of all amino acids in the sequence, then adds the mass of one water molecule to account for the terminal -H and -OH groups.

3. Importance of Protein Molar Mass

Details: Knowing a protein's molar mass is essential for various biochemical applications, including protein quantification, concentration calculations, electrophoresis, chromatography, and structural studies.

4. Using the Calculator

Tips: Enter the protein amino acid sequence using single-letter codes (e.g., "MALWMRLLPLL"). The calculator automatically removes non-amino acid characters and calculates the molar mass based on the standard amino acid masses.

5. Frequently Asked Questions (FAQ)

Q1: Does this calculator account for post-translational modifications?
A: No, this calculator provides the theoretical molecular weight based on the amino acid sequence only and does not account for modifications like phosphorylation, glycosylation, or acetylation.

Q2: Why is water mass added to the calculation?
A: Water mass (18.02 g/mol) is added to account for the hydrogen and hydroxyl groups that remain at the protein's N- and C-termini after peptide bond formation.

Q3: Are disulfide bonds considered in this calculation?
A: No, this calculator does not account for disulfide bond formation, which would slightly reduce the molecular weight due to loss of hydrogen atoms.

Q4: What about non-standard amino acids?
A: This calculator only recognizes the 20 standard amino acids. Non-standard amino acids will be ignored in the calculation.

Q5: How accurate is this calculation compared to experimental methods?
A: This provides a theoretical value. Experimental methods like mass spectrometry may yield slightly different results due to isotopic distributions and possible modifications.