Topoisomerase I

Citations & References (5)

Invitrogen™

Topoisomerase I

Topoisomerase I (DNA-relaxing enzyme) catalyzes the removal of superhelical turns from covalently closed DNA by a transient breakage and rejoiningRead more

Catalog Number	Quantity
38042024	500 U

Catalog number 38042024

Price (MXN)

Quantity:

500 U

Request bulk or custom format

Topoisomerase I (DNA-relaxing enzyme) catalyzes the removal of superhelical turns from covalently closed DNA by a transient breakage and rejoining of phosphodiester bonds. Topoisomerase I is active in the presence of EDTA.

Applications: Relaxing positively and negatively supercoiled DNA (1). Producing DNA topoisomers (2).

Source: Purified from calf thymus.

Performance and Quality Testing: Endodeoxyribonuclease, 3´ and 5´ exodeoxyribonuclease, and phosphatase assays; conversion of super-coiled DNA to relaxed DNA.

Unit Definition: One unit catalyzes the conversion of 0.5 μg of superhelical Φ X174 RF DNA to a relaxed state in 30 min. at 37°C.

Unit Reaction Conditions: 50 mM Tris-HCl (pH 7.5), 50 mM KCl, 10 mM MgCl₂ , 0.1 mM EDTA, 0.5 mM DTT, 30 μg/ml/BSA, 0.5 μg
Φ X174 RF DNA, and enzyme in 50 μl for 30 min. at 37°C.

For Research Use Only. Not for use in diagnostic procedures.

Specifications

Product TypeTopoisomerase I

Quantity500 U

Shipping ConditionWet Ice

EnzymeTopoisomerase

Unit SizeEach

Contents & Storage

Store in freezer (-5 to -30°C).

Frequently asked questions (FAQs)

What are the applications and recommended protocols for Topoisomerase I?

Topoisomerase I has two general applications: to relax supercoiled DNA, and to generate samples with defined superhelical density. Generating samples with defined superhelical density is described in Analytical Biochemistry, v.122, p. 253, by Singleton and Wells (1982).

For relaxing supercoiled DNA, use the following protocol:

1. Add 0.5 µg supercoiled PhiX 174 DNA, 50 mM TrisHCl (pH 7.5), 50 mM KCl, 10 mM MgCl2, 0.5 mM DTT, 0.1 mM EDTA, 30 µg/mL BSA, and 1 unit Topoisomerase I to a final volume of 50 µL.
2. Incubate 30 mins at 37 degrees C.
3. Analyze the treated samples on a 1% agarose gel that does not contain ethidium bromide. Stain with ethidium bromide after electrophoresis is complete.

Do you offer a pre-made buffer for use with Topoisomerase I (Cat. No. 38042024)?

No, we do not offer a pre-made buffer for use with this product.

When editing a cycle on the Procise System, I can readily delete a step, but cannot seem to insert a function into the cycle. What am I doing wrong?

When you edit a flask cycle, be sure to highlight a flask function in order to insert it. Similarly, when editing a cartridge cycle, highlight a cartridge function in order to insert it.

Citations & References (5)

Citations & References

Abstract

Prominent mitochondrial DNA recombination intermediates in human heart muscle.

Authors: Kajander O A; Karhunen P J; Holt I J; Jacobs H T;

Journal:EMBO Rep

PubMed ID:11713192

'Recombination intermediates containing four-way (Holliday) junctions are generated during DNA repair and replication in many systems, including yeast mitochondrial DNA (mtDNA). In contrast, convincing evidence for recombination in mammalian mtDNA is lacking. We have used two-dimensional agarose-gel electrophoresis to analyse non-linear forms of mtDNA in human heart muscle. Replication intermediates ... More

FtsK Is a DNA motor protein that activates chromosome dimer resolution by switching the catalytic state of the XerC and XerD recombinases.

Authors: Aussel Laurent; Barre FranÃ§ois Xavier; Aroyo Mira; Stasiak Andrzej; Stasiak Alicja Z; Sherratt David;

Journal:Cell

PubMed ID:11832210

'FtsK acts at the bacterial division septum to couple chromosome segregation with cell division. We demonstrate that a truncated FtsK derivative, FtsK(50C), uses ATP hydrolysis to translocate along duplex DNA as a multimer in vitro, consistent with FtsK having an in vivo role in pumping DNA through the closing division ... More

Sequence-specific trapping of topoisomerase I by DNA binding polyamide-camptothecin conjugates.

Authors: Wang C C; Dervan P B;

Journal:J Am Chem Soc

PubMed ID:11535069

Hairpin pyrrole-imidazole polyamides are synthetic ligands that bind in the minor groove of DNA with affinities and specificities comparable to those of DNA binding proteins. Three polyamide-camptothecin conjugates 1-3 with linkers varying in length between 7, 13, and 18 atoms were synthesized to trap the enzyme Topoisomerase I and induce ... More

Biological characterization of MLN944: a potent DNA binding agent.

Authors:Sappal DS, McClendon AK, Fleming JA, Thoroddsen V, Connolly K, Reimer C, Blackman RK, Bulawa CE, Osheroff N, Charlton P, Rudolph-Owen LA,

Journal:Mol Cancer Ther

PubMed ID:14749475

MLN944 (XR5944) is a novel bis-phenazine that has demonstrated exceptional efficacy against a number of murine and human tumor models. The drug was reported originally as a dual topoisomerase I/II poison, but a precise mechanism of action for this compound remains to be determined. Several lines of evidence, including the ... More

Sticky DNA, a long GAA.GAA.TTC triplex that is formed intramolecularly, in the sequence of intron 1 of the frataxin gene.

Authors: Vetcher Alexandre A; Napierala Marek; Iyer Ravi R; Chastain Paul D; Griffith Jack D; Wells Robert D;

Journal:J Biol Chem

PubMed ID:12161437

Friedreich's ataxia is caused by the massive expansion of GAA.TTC repeats in intron 1 of the frataxin (X25) gene. Our prior investigations showed that long GAA.TTC repeats formed very stable triplex structures which caused two repeat tracts to adhere to each other (sticky DNA). This process was dependent on negative ... More