1. What is Molecular Weight?

Molecular weight (MW) is the sum of the atomic weights of all atoms in a molecule. In biochemistry, it's often expressed in kilodaltons (kDa), where 1 kDa = 1000 g/mol.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( MW \) — Molecular weight in kilodaltons (kDa)
• \( AA\ masses \) — Array of amino acid masses in g/mol

Explanation: The calculator sums all input amino acid masses and divides by 1000 to convert to kDa.

3. Importance of Molecular Weight

Details: Molecular weight is crucial for protein characterization, SDS-PAGE analysis, chromatography, and determining protein concentration.

4. Using the Calculator

Tips: Enter amino acid masses in g/mol, separated by commas or new lines. The calculator will sum all valid numbers and convert to kDa.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between Da and kDa?
A: 1 kDa = 1000 Da (Daltons). kDa is typically used for proteins and larger biomolecules.

Q2: How accurate is this calculation?
A: The calculation is mathematically precise, but actual protein MW may vary slightly due to post-translational modifications.

Q3: Should I include water in the calculation?
A: No, the amino acid masses already account for water loss during peptide bond formation.

Q4: Can I use this for nucleic acids?
A: This calculator is designed for proteins. Nucleic acids require different calculations.

Q5: What about post-translational modifications?
A: You would need to add the mass of any modifications (phosphorylation, glycosylation, etc.) separately.