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Deoxyribonucleic acid sodium salt from Escherichia coli strain B

Genomic, unsheared

CAS Number:
EC Number:
MDL number:


for molecular biology

Quality Level


lyophilized powder

mol wt

>45 kb

storage temp.


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General description

Escherichia coli strain B is most widely studied DNA after k-12. The genomes of E coli strain B and k-12 show differences in the IS sequence elements. Strain B have B-islands and express O-specific side-chain LPS.[1] The product is unsheared genomic DNA.


50% GC; Tm = 90.5 °C


The DNAs are particularly useful for genomic analysis, including PCR, library construction in bacteriophage λ, and in heterologous pre-hybridization and hybridization protocols.
Deoxyribonucleic acid sodium salt from Escherichia coli strain B has been used for:
  • PCR reactions of genomic DNA of Gardnerella vaginalis[2]
  • nick translation and radiolabeling of dNTP[3]
  • generating standard curve for 16S rDNA quantification[4]
  • transfecting neutrophils[5]
  • testing the extraction methods[6]

Unit Definition

One unit will yield an A260 of 1.0 in 1.0 ml of 1 mM Tris-HCl, pH 7.5, with 1 mM NaCl and 1 mM EDTA (1 cm light path).

Preparation Note

Purified by anion exchange chromatography, dialyzed against a solution of 1 mM sodium chloride, 1 mM EDTA and 1 mM Trizma HCl, pH 7.5 and lyophilized at a concentration of approx. 2 units per mL. Approx. 20 A260 units per mg DNA. % GC is the percentage of G/C base pairs. Tm is the temperature at the midpoint of the thermal denaturation profile.

Analysis Note

Analyzed by gel electrophoresis and visualization after ethidium bromide staining, with single predominant band of 45 kB or greater.

Other Notes

DNA in solution will reanneal on standing at room temperature so it is recommended to boil the solution for 10 minutes and then cool on ice for at least 5 minutes prior to use.

Storage Class Code

13 - Non Combustible Solids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificate of Analysis

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Certificate of Origin

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