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Restriction Endonucleases >
Restriction Endonucleases >
SpeI |
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Recognition Site:
isoschizomers | compatible ends | single letter code
Source:
A E. coli strain that carries the SpeI gene from Sphaerotilus species (ATCC 13923).
Reagents Supplied:
NEBuffer 4 (10X)
BSA (100X)
Enzyme Properties
Activity in NEBuffers:
| NEBuffer 1: | | 75% | | NEBuffer 2: | | 100% | | NEBuffer 3: | | 25% | | NEBuffer 4: | | 100% |
When using a buffer other than the optimal (supplied) NEBuffer, it may be necessary to add more enzyme to achieve complete digestion.
Methylation Sensitivity:
| dam methylation: Not sensitive | | dcm methylation: Not sensitive | | CpG methylation: Not sensitive |
Heat Inactivation:
80°C for 20 minutes
Survival in a Reaction:
Minimum units to digest 1 µg of substrate DNA in 16 hours: 0.25 unit(s)
Reaction & Storage Conditions
Reaction Conditions:
1X NEBuffer 4
Supplemented with 100 μg/ml Bovine Serum Albumin
Incubate at
37°C.
1X NEBuffer 4:
20 mM Tris-acetate
50 mM potassium acetate
10 mM Magnesium Acetate
1 mM Dithiothreitol
pH 7.9 @ 25°C
Unit Definition:
One unit is defined as the amount of enzyme required to digest 1 µg of Adenovirus-2 DNA in 1 hour at 37°C in a total reaction volume of 50 µl.
Concentration:
10,000 units/ml and 50,000 units/ml
Unit Assay Substrate:
Adenovirus-2 DNA
Storage Conditions:
10 mM Tris-HCl
250 mM NaCl
1 mM Dithiothreitol
0.1 mM EDTA
200 µg/ml BSA
50% Glycerol
0.15% Triton X-100
pH 7.4 @ 25°C
Storage Temperature:
-20°C
Diluent Compatibility:
Diluent C
Notes
General notes:- Cleaves to leave a 5´ CTAG extension which can be efficiently ligated to DNA fragments generated by AvrII, NheI, or XbaI.
FAQs
- Are there any common problems encountered when using SpeI?
- The NEB catalog has historically stated that activity in NEBuffer4 is less than 100% yet this enzyme is now supplied with NEBuffer4. What have you changed?
- Has the conversion to NEBuffer4 altered any of the properties of the restriction enzyme?
- If I have an old tube of enzyme, what NEBuffer should I use?
- Will the new enzyme work in the originally supplied NEBuffer?
- Why is NEB switching this restriction enzyme to NEBuffer 4?
- Can SpeI be used at alternative reaction temperatures?
- Is SpeI active at 25°C?
- Does SpeI produce commonly used compatible ends?
Quality Control for Current Lot
Quality control values for a specific lot can be found on the datacard which accompanies each product.
Ligation and Re-cutting:
After a 20-fold overdigestion with SpeI, > 95%
of the DNA fragments can be ligated with T4 DNA Ligase (at a 5' termini concentration of 1-2 μM)
at 16ºC. Of these ligated fragments, > 95% can be recut with SpeI.
16-Hour Incubation:
A 50 μl reaction containing 1 μg of Adenovirus-2 DNA
and 50 units of SpeI incubated for 16 hours at 37ºC
resulted in a DNA pattern free of detectable nuclease degradation as determined by agarose gel electrophoresis.
Exonuclease Activity:
Incubation of a 50 μl reaction containing 100 units of SpeI with 1 μg of a mixture of single and double-stranded
[3H] E. coli DNA (205 cpm/μg) for 4 hours at 37ºC
released < 0.1% of the total radioactivity.
Endonuclease Activity:
Incubation of a 50 μl reaction containing 50 units of SpeI with 1 μg of
ΦX174 RF I DNA for 4 hours at 37ºC resulted
in < 20% conversion to RFII as determined by agarose gel electrophoresis.
Blue/White Screening Assay:
An appropriate vector is digested at a unique site within the
lacZα gene with a 10-fold excess of enzyme.
The vector DNA is then ligated, transformed, and plated onto Xgal/IPTG/Amp plates.
Successful expression of β-galactosidase is a function of how intact its gene remains after cloning,
an intact gene gives rise to a blue colony, removal of even a single base gives rise to a white colony.
Enzyme preparations must produce fewer than 3% white colonies to be Blue/White certified.
Reagents Sold Separately
NEBuffer 4
BSA
Legal
Patents:
New England Biolabs, Inc.: U.S. Patent No. 5,945,326
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