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Cat. No.: CRE-50 (for 50U)

Cat. No.: CRE-250 (for 250U)

Cat. No.: CRE-1k (for 1KU)

Description

Cre recombinase is a type I topoisomerase derived from bacteriophage P1 of Escherichia coli. It is also a tyrosine recombinase. It recognizes a 34bp DNA sequence called loxP, which consists of two 13bp inverted repeats flanking an 8bp spacer region. It catalyzes recombination between loxP sites, causing DNA rearrangement. The recombination products differ depending on the position and relative orientation of the loxP sites. When two single loxP sites are present, they will undergo fusion: the DNA between two loxP sites in the same orientation will be cleaved, forming a circular structure, while the DNA sequence between two loxP sites in the opposite orientation will be inverted.

Source

Cre recombinase is obtained through recombinant expression and purification in Escherichia coli (E.coli).

Applications

Catalyzes site-specific recombination between loxP sites.

Activity Definition

One unit is defined as the amount of enzyme required to achieve the maximum site-specific recombination of 250 ng control DNA in a 50 μl reaction system at 37°C for 30 minutes. The maximum recombination can be analyzed by agarose gel electrophoresis or screened through appropriate resistance plates after transformation.

Enzyme Storage Buffer

15 mM Tris-HCl (pH 8.0), 250 mM NaCl, 0.3 mg/ml BSA, 50% (v/v) Glycerol.

Inactivation or Inhibition

Heat inactivation at 70°C for 10 minutes.

Precautions

• It is recommended to heat inactivate Cre recombinase by incubating the reaction mixture at 70°C for 10 minutes before digesting DNA samples and performing agarose gel electrophoresis.
• Due to the dynamic equilibrium nature of the reaction catalyzed by Cre recombinase, only 20-30% of the substrate DNA undergoes recombination.
• Prolonging the incubation time will not improve the recombination efficiency and may even result in the generation of high molecular weight recombinant products.
• Excessive amounts of Cre recombinase in the reaction may form loxP-dependent Cre-DNA complexes, which could potentially inhibit the recombination reaction.

Storage

Store at -20°C.