1. What Is Protein Molecular Weight Calculation?

Protein molecular weight calculation determines the mass of a protein based on its amino acid sequence. The molecular weight is typically expressed in kilodaltons (kDa), where 1 kDa equals 1000 Daltons.

2. How Does The Calculator Work?

The calculator uses the formula:

Where:

• \( MW \) — Molecular weight in kilodaltons
• \( \sum \text{Amino acid MW (Da)} \) — Sum of individual amino acid masses in Daltons

Explanation: The calculator sums the molecular weights of all amino acids in the sequence and converts the total from Daltons to kilodaltons by dividing by 1000.

3. Importance Of Molecular Weight Calculation

Details: Accurate molecular weight calculation is essential for protein characterization, electrophoresis, chromatography, and various biochemical applications where protein size matters.

4. Using The Calculator

Tips: Enter the amino acid sequence using single-letter codes. The calculator automatically ignores any non-amino acid characters and calculates the total molecular weight.

5. Frequently Asked Questions (FAQ)

Q1: What are the standard molecular weights for amino acids?
A: Each amino acid has a specific molecular weight ranging from approximately 75 Da (Glycine) to 204 Da (Tryptophan).

Q2: Does this calculator account for post-translational modifications?
A: No, this calculator provides the theoretical molecular weight based solely on the amino acid sequence without modifications.

Q3: How accurate is this calculation?
A: This provides a theoretical molecular weight that is accurate for most biochemical applications, though actual experimental values may vary slightly.

Q4: Can I use three-letter amino acid codes?
A: No, this calculator only accepts single-letter amino acid codes (A, R, N, D, C, Q, E, G, H, I, L, K, M, F, P, S, T, W, Y, V).

Q5: Why is molecular weight expressed in kDa?
A: Kilodaltons provide a more convenient unit for protein sizes, as most proteins have molecular weights in the thousands of Daltons.