1. What is Molecular Weight?

Molecular weight (MW) is the sum of the atomic weights of all atoms in a molecule. For proteins, it's crucial for understanding physical properties, concentration calculations, and experimental design.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Atomic masses — Standard atomic weights of elements (in g/mol)
• Counts — Number of each atom in the molecule

Explanation: The calculator parses the chemical formula, identifies elements and their counts, then sums the products of atomic masses and counts.

3. Importance of Molecular Weight Calculation

Details: Molecular weight is essential for preparing solutions, determining molar concentrations, electrophoresis, mass spectrometry, and protein characterization.

4. Using the Calculator

Tips: Enter the chemical formula using standard element symbols (e.g., C10H16N2O3S). The formula is case-sensitive (capital letters for element symbols).

5. Frequently Asked Questions (FAQ)

Q1: What elements are supported?
A: Common biological elements (C, H, N, O, S, P) plus metals (K, Na, Ca, Mg, Fe, Zn, Cu).

Q2: How accurate is this calculator?
A: It uses standard atomic weights. For precise work, use isotopic distributions.

Q3: Can I use parentheses in formulas?
A: This simple version doesn't support parentheses or complex formulas.

Q4: What about modified amino acids?
A: For modified residues, calculate separately and add to the total.

Q5: How does this compare to ExPASy's tool?
A: This is a simplified version. For full protein analysis, use ExPASy's ProtParam.