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USER® Enzyme
neb31 cloned at NEB recombinant 37 No

Thermolabile USER II Enzyme (NEB #M5508) and Thermostable USER III Enzyme (NEB #M5509) are available.

We are excited to announce that all reaction buffers are now BSA-free. NEB began switching our BSA-containing reaction buffers in April 2021 to buffers containing Recombinant Albumin (rAlbumin) for restriction enzymes and some DNA modifying enzymes. Find more details at

USER (Uracil-Specific Excision Reagent) Enzyme (1) generates a single nucleotide gap at the location of a uracil residue.

Applications of USER include:

  • Directional RNA Seq
  • NEBNext adaptor cleavage
  • USER cloning


Figure 1: USER Enzyme

Uracil DNA glycosylase (UDG) catalyzes the excision of a uracil base, forming an abasic (apyrimidinic) site while leaving the phosphodiester backbone intact. The lyase activity of Endonuclease VIII breaks the phosphodiester backbone at the 3´ and 5´ sides of the abasic site so that base-free deoxyribose is released. USER (Uracil-Specific Excision Reagent) Enzyme, combines these two enzymatic activities to generate a single nucleotide gap at the location of a uracil residue.

Catalog # Concentration Size
M5505S 1,000 units/ml 50 units
M5505L 1,000 units/ml 250 units
Please enter a quantity for at least one size
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