Product Class: Restriction Endonuclease



High Fidelity (HF®) Restriction Enzymes have 100% activity in CutSmart™ Buffer; single-buffer simplicity means more straightforward and streamlined sample processing. HF enzymes also exhibit dramatically reduced star activity. HF enzymes are all Time-Saver™ qualified and can therefore cut substrate DNA in 5-15 with the flexibility to digest overnight without degradation to DNA. Engineered with performance in mind, HF restriction enzymes are fully active under a broader range of conditions, minimizing off-target products, while offering flexibility in experimental design.

Product Source

An E. coli strain that carries the cloned and modified BstEII-HF gene from Bacillus stearothermophilus ET (N. Welker)

Reagents Supplied

The following reagents are supplied with this product:

Store at (°C)Concentration
CutSmart® Buffer-2010X
Gel Loading Dye, Purple (6X)256X

Properties and Usage

Unit Definition

One unit is defined as the amount of enzyme required to digest 1 μg of λ DNA in 1 hour at 37°C in a total reaction volume of 50 μl.

Reaction Conditions

1X CutSmart® Buffer
Incubate at 37°C

1X CutSmart® Buffer:
50 mM Potassium Acetate
20 mM Tris-acetate
10 mM Magnesium Acetate
100 μg/ml BSA
pH 7.9 @ 25°C

Activity in NEBuffers

NEBuffer 1.1: 10%
NEBuffer 2.1: 10%
NEBuffer 3.1: 10%
CutSmart® Buffer: 100%

Diluent Compatibility

Storage Temperature


Storage Conditions

10 mM Tris-HCl
50 mM KCl
1 mM DTT
0.1 mM EDTA
200 μg/ml BSA
50% Glycerol
pH 7.4 @ 25°C

Heat Inactivation


Methylation Sensitivity

dam methylation: Not Sensitive
dcm methylation: Not Sensitive
CpG Methylation: Not Sensitive

Heat Inactivated


Quality Control

Quality Control Assays

The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page.
  • Endonuclease Activity (Nicking):
    The product is tested in a reaction containing a supercoiled DNA substrate. After incubation for 4 hours the percent converted to the nicked form is determined by agarose gel electrophoresis.
  • Exonuclease Activity (Radioactivity Release):
    The product is tested in a reaction containing a radiolabeled mixture of single and double-stranded DNA. After incubation for 4 hours the exonuclease activity is determined by the % release of radioactive nucleotides.
  • Ligation and Recutting (Terminal Integrity):
    After an over-digestion of DNA with a restriction endonuclease the percentage of the DNA fragments ligated with T4 DNA ligase and the percentage that can be recut are determined by agarose gel electrophoresis.
  • Non-Specific DNase Activity (16 hour):
    The product is tested for non-specific nuclease degradation in a reaction containing a DNA substrate. After incubation for 16 hours there is no detectable degradation of the DNA substrate as determined by agarose gel electrophoresis.

Supporting Documents

The Certificate of Analysis (COA) is a signed document that includes the storage temperature, expiration date and quality control's for an individual lot. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]_[Lot Number]
The Specification sheet is a document that includes the storage temperature, shelf life and the specifications designated for the product. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]
The following is a list of Safety Data Sheet (SDS) that apply to this product to help you use it safely.
The Product Summary Sheet, or Data Card, includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at or fill out the Technical Support Form for appropriate document.


  1. Of the over 3,000 known restriction endonucleases, very few produce extensions of more than 4 bases.
  1. What does HF® refer to following the name of a restriction enzyme?
  2. What effect does BSA have on the performance of NEB’s restriction enzymes when included in the new buffers?
  3. Do I have to set-up digests with Time-Saver™ qualified enzymes for 5-15 minutes? Can I digest longer?
  4. How can I access the old NEBuffer Activity Chart?
  5. I tested your restriction enzyme on the substrate DNA recommended by NEB, and it appears to be active, however it does not digest my DNA. What could be the reason?
  6. My restriction enzyme used to work well in the old NEBuffer but the new Performance chart indicates it has lower activity even though the only difference is the addition of BSA and removal of DTT to the new buffers. Why?
  7. Is Gel Loading Dye, Purple (6X) or Gel Loading Dye, Purple (6X), no SDS compatible with other DNA binding dyes such as SYBR® and GelRed™ during gel electrophoresis?
  8. Can Gel Loading Dye, Purple 6X (B7024) be stored in cold temperatures?
  1. Optimizing Restriction Endonuclease Reactions
  2. Double Digest Protocol with Standard Restriction Enzymes