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FAQ |  | Competent Cells FAQ
To see FAQs about a specific Competent Cells, see links from the specific product's page.
Q1: Which strain of Competent E.coli should I use for general cloning?
Q2: Does New England Biolabs offer strains of Competent E.coli suited for protein expression?
Q3: What is LysY?
Q4: Does New England Biolabs offer a methyltransferase free strain of Competent E.coli?
Q5: What are the advantages of New England Biolabs' competent cells?
Q6: What formats are competent cells available in?
Q1: Which strain of Competent E.coli should I use for general cloning?
A1: NEB 5-alpha Competent E.coli (NEB #C2991) are a high efficiency derivative of DH5α™, the industry standard cloning strain. NEB Turbo Competent E.coli (NEB #C2984) and NEB 5-alpha F´Iq Competent E.coli (NEB #C2992) allow potentially toxic genes to be cloned due to tight control of expression by lac Iq and are suitable for blue/white screening. NEB Turbo Competent E.coli (NEB #C2984) bring unmatchable speed to your transformations with visible colonies after just 6.5 hours. NEB 10-beta Competent E.coli (NEB #C3019) are a derivative of DH10B™ and can be used for transforming large plasmids and BACs. Dam-/dcm- Competent E.coli (NEB #C2925) can be used for methylation-free plasmid growth.
Q2: Does New England Biolabs offer strains of Competent E.coli suited for protein expression?
A2: Yes, we have six strains for protein expression. NEB Express (NEB #C2523) is an enhanced BL21 derivative, available with or without the added control of IPTG-induced expression of non-T7 plasmids from lacIq (NEB Express Iq, NEB #C3037). T7 Express Competent E.coli (NEB # C2566H) and T7 Express Iq Competent E. coli (NEB #C2833H) are enhanced derivatives of BL21(DE3). The lacIq strain allows for tighter control of expression. Both are available with the lysY feature for exceptional control of expression. (T7 Express lysY, NEB #C3010 and T7 Express lysY/Iq, NEB #C3013)
Q3: What is LysY?
A3: LysY is a variant of T7 lysozyme lacking amidase activity making the cells less susceptible to lysis during induction, while retaining the ability to inhibit T7 RNA Polymerase. Basal expression of the target gene is minimized without inhibiting IPTG-induced expression. LysY is encoded on a single-copy miniF plasmid that does not require antibiotic selection for propagation.
Q4: Does New England Biolabs offer a methyltransferase free strain of Competent E.coli?
A4: Yes, dam-/dcm- Competent E.coli (NEB #C2925H) are methyltransferase deficient chemically competent E.coli cells suitable for growth of plasmids free of dam and dcm methylation.
Q5: What are the advantages of New England Biolabs' competent cells?
A5: - No animal products used
- T1 phage resistance
- Media and control plasmid included
- A variety of convenient formats, including single use transformation tubes and, on request, 96 well plates
- Bulk sales capabilities with custom packaging
Q6: What formats are competent cells available in?
A6: For your convenience, we offer all of these strains in two formats; 20 single-use transformation tubes (50 µl each) or 6 tubes containing 200 µl each. Both formats are supplied with SOC Outgrowth Media and a pUC19 plasmid control. The most popular cloning strain, NEB 5-alpha is offered at a subcloning efficiency for substantial value. NEB 5-alpha, NEB 10-beta and NEB Turbo are also available in electrocompetent formats. 96 well plate formats are available, on request, for high volume users.
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