pET-21b(+) DNA - Novagen | Molecular Cloning & Protein Expression

REF #: 3200305
Short description
  • pET-21b(+) DNA – Novagen
  • Carries an N-terminal T7-Tag sequence
  • Has an optional C-terminal His-Tag sequence
  • Can be used with pET-21a-d(+) vectors

For more information, please visit the product page.

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  • Procurenet Team Tshim Sha Tsui
    Hong Kong Hong Kong 3 years
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  • 7 Days Return Back Policy
  • 2 Days Cancellation Policy
  • Ship Only

The pET-21b(+) DNA from Novagen is a highly reliable and efficient tool for molecular cloning and protein expression experiments. It is designed to carry and express target genes in a variety of host cells, making it an ideal choice for both academic and industrial research applications.

Key Features:

  • Carries an N-terminal T7-Tag sequence, allowing for easy detection and purification of the expressed target protein.
  • Has an optional C-terminal His-Tag sequence, enabling efficient purification of the expressed protein using nickel-affinity chromatography.
  • Compatible with Novagen's pET-21a-d(+) vectors, providing a versatile system for cloning and expression of a wide range of target genes.


The pET-21b(+) DNA is a high-quality plasmid designed for use in molecular biology research. It consists of a double-stranded circular DNA molecule containing the following elements:

  • An origin of replication - allows for replication of the plasmid in the host cell.
  • Ampicillin resistance gene - confers resistance to ampicillin, enabling selection of transformed cells.
  • T7 promoter sequence - drives expression of the target gene under the control of the T7 RNA polymerase.
  • N-terminal T7-Tag sequence - facilitates detection and purification of the expressed protein.
  • Optional C-terminal His-Tag sequence - enables purification of the expressed protein using nickel-affinity chromatography.
  • Multiple cloning sites (MCS) - provides a range of restriction enzyme recognition sites for convenient insertion of target genes.


The pET-21b(+) DNA is compatible with a wide range of host cells commonly used for protein expression, such as E. coli strains, making it a versatile choice for different research needs. It is particularly suitable for researchers who require high-level expression of recombinant proteins for biochemical, biophysical, structural, or functional studies.

When using pET-21b(+) DNA, it is recommended to follow the standard protocols for molecular cloning and transformation. Briefly, the plasmid can be propagated, isolated, and purified using standard techniques such as alkaline lysis and column purification. The target gene can then be easily inserted into the multiple cloning sites using appropriate restriction enzymes. The resulting construct can be transformed into suitable host cells, and protein expression can be induced using IPTG or other inducer molecules.

For optimal results, it is advisable to verify the correct orientation and integrity of the insert in the pET-21b(+) DNA construct through appropriate sequencing methods. This ensures the successful expression of the desired protein of interest and minimizes the chances of unintended mutations or deletions.

It is worth noting that the pET-21b(+) DNA is not supplied with competent cells for transformation. Therefore, researchers should use their preferred competent cells or purchase them separately, depending on their specific requirements.

For more information, please visit the product page at link.

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