5-alpha Electrocompetent E. coli |NEB酶试剂 New England Biolabs

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NEB® 5-alpha Electrocompetent E. coli

NEB 5-alpha Electrocompetent Competent E. coli is a derivative of the popular DH5α. It is T1 phage resistant and endA deficient for high-quality plasmid preparations. 

  • Optimized for high efficiency transformation by electroporation
  • No dry ice surcharge on competent cell shipments
  • Outgrowth medium included
  • Free of animal products
  • Also available in High efficiency chemical format
  • Refer to our Electroporation Tips


5-alpha Electrocompetent E. coli |

Differences between electrocompetent and chemically competent cells



NEB 5-alpha Electrocompetent E. coli cells are optimized for high transformation efficiency by electroporation. These cells are ideal for DNA library constructions and all cloning purposes.


  • DH5α™ derivative
  • Transformation efficiency: >1 x 1010 cfu/µg pUC19 DNA
  • Efficient transformation of unmethylated DNA derived from PCR, cDNA and many other sources (hsdR)
  • Activity of nonspecific endonuclease I (endA1) eliminated for highest quality plasmid preparations
  • Suitable for blue/white screening by α-complementation of the β-galactosidase gene (Φ80Δ lacZM15)
  • Resistance to phage T1 (fhuA2)
  • Reduced recombination of cloned DNA (recA1)
  • K12 Strain
  • Free of animal products


fhuA2Δ(argF-lacZ)U169 phoA glnV44 Φ80Δ (lacZ)M15 gyrA96 recA1 relA1 endA1 thi-1 hsdR17

Discontinued Products

  • 特性和用法

    Antibiotic for Plasmid Selection

    用于质粒筛选的抗生素 使用浓度
    Ampicillin 100 µg/ml
    Carbenicillin 100 µg/ml
    Kanamycin 30 µg/ml
    Streptomycin 25 µg/ml
    Tetracycline 15 µg/ml


    • Ships on dry ice


    • none

  • 优势和特性


    Electroporation Tips

    1. Electroporation cuvettes and microcentrifuge tubes should be pre-chilled on ice. 
    2. Electrocompetent cells should be thawed on ice and suspended well by carefully flicking the tubes. 
    3. Once DNA is added to the cells, electroporation can be carried out immediately. It is not necessary to incubate DNA with cells. The maximum recommended volume of a DNA solution to be added is 2.5 µl. Addition of a large volume of DNA decreases transformation efficiency. 
    4. Contaminants such as salts and proteins can lower electroporation efficiency. Ideally, DNA for transformation should be purified and suspended in water or TE. Transformation efficiency is more than 10-fold lower for ligation mixtures than the control pUC19 plasmid due to the presence of ligase and salts. If used directly, ligation reactions should be heat-inactivated at 65°C for 20 min and then diluted 10-fold. For optimal results, spin columns (NEB #T1030) are recommended for cleanup of ligation reactions.
    5. Electroporation conditions vary with different cuvettes and electroporators. If you are using electroporators or cuvettes not specified in the protocol, you may need to optimize the electroporation conditions. Cuvettes with 1mm gap are recommended (e.g. BTX Model 610/613 and Bio-Rad #165-2089). Higher voltage is required for cuvettes with 2 mm gap. 
    6. Arcing may occur due to high concentration of salts or air bubbles.
    7. It is essential to add recovery medium to the cells immediately after electroporation. One minute delay can cause a 3-fold reduction in efficiency.


    DNA Effects on Transformation Efficiency and Colony Output: 5-alpha Electrocompetent E. coli |
    Electroporation efficiency remains extremely high up to about 10 ng of input DNA, then decreases at higher DNA concentrations.

  • 相关产品


    • NEB® 5-alpha Competent E. coli (High Efficiency)
    • NEB® 5-alpha Competent E. coli (Subcloning Efficiency)
    • NEB® 5-alpha F’ Iq Competent E. coli (High Efficiency)
    • SOC Outgrowth Medium
    • NEB® 10-beta Electrocompetent E. coli
    • ElectroLigase®
    • phi29 DNA Polymerase
    • Monarch® Plasmid Miniprep Kit 
    • Monarch® DNA Gel Extraction Kit
    • Monarch® PCR & DNA Cleanup Kit (5 μg)

  • 注意事项
    1. CAUTION: This product contains DMSO, a hazardous material. Review the MSDS before handling.
    2. STORAGE AND HANDLING: Competent cells should be stored at -80°C. Storage at -20°C will result in a significant decrease in transformation efficiency. Cells lose efficiency whenever they are warmed above -80°C, even if they do not thaw.

操作说明、说明书 & 用法

  • 操作说明
    1. Electroporation Protocol (C2989)

  • 使用指南
    • Additional E. coli Strain Genotypes
    • Electroporation Tips
    • Genetic Markers
    • McrA, McrBC and EcoKI Strain Phenotypes
    • Traditional Cloning Quick Guide

工具 & 资源

  • 选择指南
    • Characteristics of Select E.coli Strains
    • Competent Cell Product Comparison

  • Web 工具
    • Competitor Cross-Reference Tool
    • NEBcloner®

FAQs & 问题解决指南

  • FAQs
    1. How should I calculate the Electrotransformation efficiency (C2989)?
    2. What are the solutions/recipes (C2989)?
    3. What are the strain properties (C2989)?
    4. How should I store SOC Outgrowth Medium? The SOC I received with my competent cells recommends storage at either room temperature or 4°C, however, when I purchase it as a stand alone product, it recommends storing it at 4°C. Which is better?
    5. How should fragments be prepared for assembly using NEBuilder HiFi?

引用 & 技术文献

  • 引用文献


    5-alpha Electrocompetent E. coli | Powered by Bioz See more details on Bioz


    • Singh A, Minia I, Droll D, Fadda A, Clayton C, Erben E (2014) Trypanosome MKT1 and the RNA-binding protein ZC3H11: interactions and potential roles in post-transcriptional regulatory networks Nucleic Acids Res; 42(7), 4652-68. PubMedID: 24470144, DOI: 10.1093/nar/gkt1416

质控、安全 & 法规

  • 质控分析
    每一新批次的 NEB 产品都要经过质控,以满足指定的质量标准,对特定产品的质量标准和每一批次的检测数据可以通过产品说明表格、COA、产品信息卡或者产品手册进行查阅或下载。关于 NEB 产品质控的详细信息,可从此处查阅。

  • 产品说明与变更通知



    • C2989K_v1

  • CoA
    CoA 文件包含单个批次产品的储存温度、有效期和质控,这些文件的命名规则如下: [货号]_[规格]_[版本]_[Lot#]

    • C2989K_v1_0941702
    • C2989K_v1_0951705
    • C2989K_v1_0961706
    • C2989K_v1_0921612
    • C2989K_v1_0921701
    • C2989K_v1_0931702
    • C2989K_v1_0951704
    • C2989K_v1_0961704
    • C2989K_v1_0961707
    • C2989K_v1_0971709
    • C2989K_v1_0971710
    • C2989K_v1_0981708
    • C2989K_v1_0981711
    • C2989K_v1_0991709
    • C2989K_v1_1001709
    • C2989K_v1_1011709
    • C2989K_v1_0981712
    • C2989K_v1_0991801
    • C2989K_v1_0991802
    • C2989K_v1_1011804
    • C2989K_v1_10011194
    • C2989K_v1_10015492
    • C2989K_v1_10021464
    • C2989K_v1_10021812
    • C2989K_v1_10027936
    • C2989K_v1_10030900
    • C2989K_v1_10033105
    • C2989K_v1_10036617
    • C2989K_v1_10040976
    • C2989K_v1_10042693
    • C2989K_v1_10044804
    • C2989K_v1_10047648
    • C2989K_v1_10050480
    • C2989K_v1_10056410
    • C2989K_v1_10054063
    • C2989K_v1_10059028
    • C2989K_v1_10060045
    • C2989K_v1_10061983
    • C2989K_v1_10066420
    • C2989K_v1_10069405
    • C2989K_v1_10077118
    • C2989K_v1_10079067
    • C2989K_v1_10081197
    • C2989K_v1_10083744
    • C2989K_v1_10086608
    • C2989K_v1_10090673

  • SDS
    以下 SDS 文件可以帮助您安全地使用该产品

    • NEB® 5-alpha Electrocompetent E. coli