Protein Weight Calculator Expasy

Protein Molecular Weight Calculation:

\[ MW = \sum_{i=1}^{n} (AA_i \times w_i) \]

Molecular Weight (MW):

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1. What is Protein Molecular Weight Calculation?

Protein molecular weight calculation estimates the mass of a protein based on its amino acid sequence. This calculator uses standard amino acid weights from the Expasy database to provide accurate molecular weight estimates.

2. How Does the Calculator Work?

The calculator uses the following formula:

\[ MW = \sum_{i=1}^{n} (AA_i \times w_i) \]

Where:

\( MW \) — Molecular weight in daltons
\( AA_i \) — Amino acid at position i
\( w_i \) — Weight of amino acid in daltons (Expasy values)
\( n \) — Total number of amino acids in the sequence

Explanation: The calculator sums the weights of all individual amino acids in the protein sequence using standard Expasy amino acid weights.

3. Importance of Molecular Weight Calculation

Details: Knowing a protein's molecular weight is essential for various applications including protein purification, gel electrophoresis, mass spectrometry, and biochemical characterization.

4. Using the Calculator

Tips: Enter the protein amino acid sequence using single-letter codes. The sequence should contain only standard amino acid characters (A, R, N, D, C, E, Q, G, H, I, L, K, M, F, P, S, T, W, Y, V).

5. Frequently Asked Questions (FAQ)

Q1: What are Expasy amino acid weights?
A: Expasy (Expert Protein Analysis System) provides standardized molecular weights for amino acids that are widely accepted in the scientific community.

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: What about N-terminal and C-terminal groups?
A: The calculation includes the complete molecular weight of each amino acid residue, accounting for water loss during peptide bond formation.

Q4: Can I use three-letter amino acid codes?
A: No, this calculator only accepts single-letter amino acid codes without spaces or special characters.

Q5: How accurate is this calculation?
A: This provides the theoretical molecular weight based on standard amino acid weights. Actual experimental values may vary slightly due to isotopic distributions and other factors.