Home › Failure Case Library › Star Activity Producing Extra Bands
Restriction Enzyme Digest moderate

Star Activity Producing Extra Bands

Symptom
Extra DNA bands appear on gel beyond expected digest fragments, indicating cleavage at non-canonical recognition sequences due to relaxed enzyme specificity.
Common Causes
  1. 1 Incorrect reaction buffer used instead of enzyme-recommended buffer
  2. 2 Excessive enzyme units in reaction causing off-target cleavage
  3. 3 Glycerol concentration >5% v/v from adding >10% enzyme volume to reaction
  4. 4 Prolonged incubation time beyond minimum required for complete digestion
Solutions
  1. 1 Use the manufacturer-recommended buffer supplied with the restriction enzyme
  2. 2 Decrease enzyme units to minimum required for complete digestion
  3. 3 Ensure enzyme volume does not exceed 10% of total reaction volume (keeping glycerol ≤5% v/v)
  4. 4 Reduce incubation time to minimum required for complete digestion
  5. 5 Use High-Fidelity (HF®) restriction enzymes engineered for reduced star activity
Related Video (3)
Addgene ★ 88
Restriction Digest Analysis
"Directly demonstrates restriction enzyme digest setup, buffer selection, and gel band interpretation relevant to diagnosing star activity."
YouTube (Curated Tutorials) ★ 60
Molecular Cloning explained for Beginners
"Covers general molecular cloning workflow including restriction digest context, useful for beginners to understand where the digest step fits but not specific to star activity troubleshooting."
Bilibili (China-Accessible Mirrors) ★ 55
Hands-on plasmid construction guide
"Hands-on plasmid construction protocol likely includes restriction digest steps and reagent handling, providing practical context where buffer mistakes occur."
Source: neb.com ↗
← Back to all cases