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BL21 (DE3) chemically competent E. cells for High Level Protein Expression

Amid Biosciences

BL21 (DE3) Chemically Competent E. coli Cells | Recombinant Proteins Production

$ 120.00

BL21(DE3) chemically competent E.coli cells are suitable for transformation, high-level expression and production of recombinant proteins in bacterial systems. The strain lacks the lon and ompT proteases thus promoting stability of recombinant proteins. BL21(DE3) strain carries a copy of the T7 RNA polymerase under control of the IPTG inducible lacUV5 promoter, and as a result, is ideal for controlled expression of both E. coli and T7 promoter driven constructs.  

Compatible Expression Vectors/Promoters: Ptac, Ptrc, Plac, PlacUV5, ParaBAD, PrhaBAD, T7 

The transformation efficiency is  ≥ 1x107 cfu/μg pUC19 plasmid DNA.

BL21 (DE3) chemically competent E. coli cells are supplied as a pack of 10 ready-to-use 100 μl/tube aliquots.

Electrocompetent BL21 (DE3) E.coli cells are also available.

Bulk quantities and custom packaging are available at very competitive prices for all Competent Cells. 

Catalog # BL21-201

 E. coli genotype: fhuA2 [lon] ompT gal (λ DE3) [dcm] ∆hsdS.

λ DE3 = λ sBamHIo ∆EcoRI-B int::(lacI::PlacUV5::T7 gene1) i21 ∆nin5


  • Ideal for expressing proteins in E.coli.
  • BL21(DE3) cells carry the lambda DE3 lysogen for expression from vectors utilizing the T7 promoter.

Storage: - 80°C. Thaw on ice only before use. Do not re-freeze. 

Shipping:  Product requires shipping on dry ice. Please contact for shipment estimates. 


This product is intended for LABORATORY RESEARCH USE ONLY. Not for diagnostic or therapeutic use.


Miroux B, Walker JE. Over-production of proteins in Escherichia coli: mutant hosts that allow synthesis of some membrane proteins and globular proteins at high levels. (1996) J. Mol. Biol. 260: 289.


Transformation Protocol

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