DNA to Protein Size Calculator

Protein Size Calculation:

\[ \text{Protein Size (kDa)} = \frac{\text{DNA Length (bp)}}{3} \times \text{Average AA Weight (Da)} \div 1000 \]

Estimated Protein Size:

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1. What is the DNA to Protein Size Calculation?

This calculation estimates the molecular weight of a protein based on the length of its coding DNA sequence. It's useful for molecular biology research, protein expression studies, and experimental design.

2. How Does the Calculator Work?

The calculator uses the following equation:

\[ \text{Protein Size (kDa)} = \frac{\text{DNA Length (bp)}}{3} \times \text{Average AA Weight (Da)} \div 1000 \]

Where:

DNA Length — Length of the coding DNA sequence in base pairs (bp)
Average AA Weight — Average molecular weight of an amino acid (typically 110 Da)
Division by 3 — Accounts for 3 nucleotides coding for each amino acid
Division by 1000 — Converts from Daltons to kilodaltons (kDa)

Explanation: The equation first calculates the number of amino acids by dividing DNA length by 3, then multiplies by average amino acid weight to get the protein's molecular weight.

3. Importance of Protein Size Estimation

Details: Knowing the approximate size of a protein helps in experimental design for SDS-PAGE, chromatography, protein purification, and expression system selection.

4. Using the Calculator

Tips: Enter the length of your coding DNA sequence in base pairs. The default average amino acid weight is 110 Da, which can be adjusted if your protein has an unusual amino acid composition.

5. Frequently Asked Questions (FAQ)

Q1: Why use 110 Da as the average amino acid weight?
A: 110 Da is the typical average molecular weight of amino acids in proteins, accounting for their natural abundance and post-translational modifications.

Q2: How accurate is this estimation?
A: It provides a rough estimate. Actual protein size may vary due to post-translational modifications, signal peptides, or unusual amino acid composition.

Q3: Should I include non-coding regions in the DNA length?
A: No, only include the length of the coding sequence (CDS) that will be translated into protein.

Q4: What if my protein has many heavy amino acids?
A: You can adjust the average amino acid weight upward (e.g., 115-120 Da) if your protein is rich in tryptophan, tyrosine, etc.

Q5: Can this be used for protein expression yield estimation?
A: No, this only calculates molecular weight. Expression yield depends on many other factors like expression system and conditions.