Restriction Enzyme Digest Calculator
Calculate the volume of restriction enzyme needed to digest a given amount of DNA. Essential for molecular cloning and DNA analysis workflows.
Restriction Enzyme Digest
basicCalculate enzyme volume needed for DNA restriction digest
Formula
Units needed = DNA (μg) × 5-10 U/μg
How It Works
A standard restriction digest uses 5-10 units of enzyme per microgram of DNA. The calculator determines the volume of enzyme stock solution to add to your reaction.
Total Units = DNA (μg) × Units per μg DNA
Enzyme Volume = Total Units / Enzyme Concentration (U/μL)
Note: Always keep enzyme volume below 10% of total reaction volume to avoid glycerol inhibition, and use the appropriate buffer.
Example
Digest 1 μg of plasmid DNA with EcoRI at 10 U/μL concentration:
Total Units = 1 μg × 5 U/μg = 5 U
Enzyme Volume = 5 U / 10 U/μL = 0.50 μL
Frequently Asked Questions
How many units of enzyme should I use per μg of DNA?
Standard digest: 5-10 U/μg DNA. For plasmid DNA, 5 U/μg is usually sufficient. For genomic DNA, use 10 U/μg for complete digestion. Overnight digests can use less enzyme.
Why should enzyme volume stay under 10% of total reaction?
Restriction enzymes are stored in 50% glycerol. Adding too much glycerol (>5% final) can cause star activity — where the enzyme cuts at non-specific recognition sites.