Ligation Calculator
Determine the exact mass of insert DNA required for an optimized ligation reaction. Ensures correct stoichiometric ratios to maximize cloning efficiency.
Reaction Parameters
Specify vector size, vector mass, insert size, and molar ratio.
Required Insert Mass
* Stoichiometric amount for optimal sticky-end or blunt-end cloning.
Expert Tip
Use a 3:1 molar ratio of insert-to-vector for cohesive (sticky) ends. For blunt-end ligations, increasing the ratio to 5:1 or 10:1 yields higher cloning efficiency.
Methodology & Ligation Ratio
Ligation Formula
The mass of insert DNA required is computed stoichiometrically based on the molecular weights (which are proportional to length in base pairs):
Troubleshooting Ligations
If transformation yields no colonies:
- • Verify that the vector is dephosphorylated if using a single restriction enzyme to prevent self-ligation.
- • Check the activity of T4 DNA Ligase and buffer containing fresh ATP.
How to Calculate DNA Ligation Ratios
Ligation joins insert DNA and vector DNA. The stoichiometry must be precise for high cloning efficiency:
Identify DNA Sizes and Vector Mass
Note vector size (kb), insert size (kb), and the amount of vector DNA (ng) you will use.
Choose the Molar Ratio
A 3:1 ratio (insert to vector) is recommended for cohesive ends, whereas 5:1 or 10:1 works best for blunt ends.
Calculate Insert Mass
Use the formula: Insert Mass (ng) = Vector Mass (ng) × (Insert Size / Vector Size) × Molar Ratio.
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