1. What is mRNA Molecular Weight?

The molecular weight (MW) of an mRNA molecule is the sum of the atomic weights of all atoms in the molecule. It's important for determining concentration, synthesis yield, and dosing in mRNA-based therapeutics.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( base\_masses \) — Molecular weights of individual nucleotides
• Standard nucleotide weights: A=329.2, U=306.2, C=305.2, G=345.2 g/mol
• 5' cap adds 7-methylguanosine (m7G) and triphosphate bridge
• Each internucleotide linkage accounts for -H₂O + PO₃

3. Importance of mRNA MW Calculation

Details: Accurate molecular weight is crucial for:

• Determining molar concentration of mRNA samples
• Calculating synthesis yield and purity
• Formulating mRNA-based vaccines and therapeutics
• Normalizing transfection experiments

4. Using the Calculator

Tips:

• Enter the mRNA sequence (A, U, C, G only)
• Select appropriate 5' cap modification if present
• Specify Poly-A tail length if applicable
• The calculator automatically accounts for backbone phosphates

5. Frequently Asked Questions (FAQ)

Q1: Does this account for modified nucleotides?
A: The basic calculator uses standard nucleotides. For modified bases, you'll need to adjust the molecular weights manually.

Q2: How accurate is this calculation?
A: It provides theoretical MW based on nucleotide composition. Actual MW may vary slightly due to isotopic distribution.

Q3: Why include the 5' cap in calculations?
A: The cap adds significant mass (≈900 g/mol) and is present in most therapeutic mRNAs.

Q4: How does Poly-A tail affect MW?
A: Each adenine nucleotide adds 329.2 g/mol plus backbone phosphate.

Q5: Can I calculate molar concentration from this?
A: Yes, using the formula: concentration (µg/µL) × 10⁶ ÷ MW (g/mol) = molarity (µM).