pBR322 is a 4363 bp vector purified from Escherichia coli.

• Liquid, soluble in water
• Supplied in a 10 mM Tris-HCl, 1 mM EDTA buffer at a concentration of 0.5 ug/ul
• pH 7.5
• Store at –20 °C

It is one of the most commonly used cloning vectors, that confers resistance to ampicillin and tetracycline. It contains single restriction sites for Pst I and Pvu I within the ampicillin-resistance gene (ampr) and single restriction sites for BamH I, Sal I, Sph I, EcoR V, Nru I and Xma III within the tetracycline-resistance gene (tetr).

Plasmid pBR322 was one of the first multipurpose cloning vectors constructed for use in Escherichia coli. This plasmid and derivatives have been used for a number of purposes including cloning, selection and expression of recombinant molecules, construction of shuttle vectors and vectors for nucleotide sequencing, studies of elements involved in gene expression, as plasmid DNA standards, and as a model system for studies on prokaryotic plasmid replication. Note-Elevated temperatures and/or multiple freeze/thaw cycles will cause some of the ccDNA to convert to ocDNA.

pBR322 DNA exists in supercoiled (closed circular) DNA (ccDNA) and linear DNA (both open circular pBR322 plasmid adn E. coli chromosomal contamination) (ocDNA) in an approximate ratio of 90:10.