Strep-tag® diagnostic/assay system

Improved Diagnosis by Immobilization with Strep-Tactin®
  • Oriented presentation of the antigen on the plate surface
  • Improved accessibility for the antibody
  • High signal to noise ratio
  • Specific and mild adsorption leaving the antigen intact
  • Highly constant assay conditions (standard protocol, no individual optimization)
  • High reproducibility

Application tools

Recommended paper:

For reference of Strep-tag technology please quote "Schmidt TGM and Skerra A, 2007. The Strep-tag system for one-step purification and high-affinity detection or capturing of proteins. NATURE PROTOCOLS 2, 1528-1535."
abstract

Reprints are available from the authors upon request.

Strep-Tactin® coated microplates

Fast, selective and sensitive assay for 8 to 96 samples

Microplate consisting of twelve 8-well strips coated with Strep-Tactin

Ready-to-use Strep-Tactin coated 8-well strips provide the power of our Strep-tag system in a solid-phase, multi-well format for convenient assays and high throughput screenings of biomolecules tagged with Strep-tag II. The strips are supplied framed in sets of 12, resulting in a 96-well configuration compatible with standard multichannel pipettes and automated plate washers and plate readers.

Features and benefits

  • Oriented immobilization of recombinant proteins with N-terminal, C-terminal or internal Strep-tag II
  • Effective screening procedures
  • Minimal non-specific binding
  • High and constant activity
  • Minimal coefficients of variation (cv)


Principle and properties

The Strep-tag assay system uses 8-well strips coated with Strep-Tactin, allowing Strep-tag II fusion proteins to be selectively captured from complex mixtures of molecules. The biomolecules are presented to interacting partners in a uniform manner which results in reliable and reproducible assay formats.


Procedure

Strep-Tactin coated microplates (12 x 8-well strips) are offered freeze dried and ready-to-use. Solutions containing the Strep-tag II fusion protein can be applied without any prior wetting step.


Applications

  • Antibody or serum screening (see Figure on the left)
  • Diagnostic assays
  • Expression cloning
  • Protein interaction studies
  • Screening of engineered enzymes
  • Drug screening

Specifications of Strep-Tactin coated microplates

Strep-tag® fusion protein binding capacity 100 ng Strep-tag II fusion protein/well
Intra- and inter-assay variance (cv) < 1.6% and < 3.0%, respectively
Max. volume per well 300 µl
Optimal pH 8.0
Stability > 1 year at 4 °C
Storage 4 °C
Shipment RT


Capture of functional target proteins on Strep-Tactin® coated microplates

Determination of an alkaline phosphatase (AP) Strep-tag® II fusion protein

General conditions
1. Strep-Tactin coated microplate was incubated with different amounts of recombinant E. coli alkaline phosphatase/Strep-tag II fusion protein.
2. Washing cycles.
3. Colorimetric determination of bound AP-activity.		 High stability of interaction Low intra-assay variance
(after 3 washing cycles)

H. pylori urease as antigen in a solid phase immunoassay
General conditions
1. Strep-Tactin coated microplate was incubated with recombinant
H. pylori urease/Strep-tag II fusion protein, followed by 3 washing cycles.
2. Second incubation with human sera followed by 3 washing cycles.
3. Third incubation with rabbit anti-human lgG conjugated to peroxidase, followed by 3 washing cycles.
4. Colorimetric determination of bound peroxidase
activity.		 Specific determination of H. pylori infection



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Order information
see also "how to order"

product amount cat. no. order & prices
Strep-Tactin coated microplates
(12 x 8 wells)		 1 plate 2-1501-001 online order
5 plates 2-1501-050 online order


StrepMAB-Immo coated microplates; 96well

Highly reproducible microassays of SerAla- Strep-tag II fusion proteins

Features

  • Ready-to-use 96well plates for your own protein assay
  • Efficient immobilization* of minute amounts of SerAla- Strep-tag II fusion proteins saves your starting material
  • High wash stability during the assay (nearly no off-rate!)
  • High reproducibility

*KD StrepMAB-Immo:SerAla- Strep-tag II ~ 1 pM

Microplate assay showing efficient binding of minute amunts of SerAla- Strep-tag II fusion protein (BAP) until saturation:
BAP = bacterial alkaline phosphatase,
C-terminally fused with Strep-tag II via SerAla linker
 The new StrepMAB-Immo coated microplates can be used for efficient, mild and oriented immobilization of SerAla- Strep-tag II fusion proteins for ELISA or other assays for protein analysis. Also small amounts of such proteins are bound with high efficiency to the microplate (see graphic on the left) and will not elute during the assay due to nearly irreversible binding activity of StrepMAB-Immo.

Specifications of StrepMAB-Immo coated microplates

Plate type 12 x 8-well strips and frame, transparent, flat bottom
StrepMAB-Immo coated area 100 µl
Blocked area 300 µl
Strep-tag II fusion protein binding capacity ~3 pmol Strep-tag II fusion protein per 100 µl incubation volume determined for bacterial alkaline phosphatase)
Max. volume per well 300 µl
Specificity Nearly irreversible binding of C-terminally fused Strep-tag II with SerAla linker (rec. protein seq.- SerAla-TrpSerHisProGlnPheGluLys). The Strep-tag will be linked automatically to the C-terminus of the recombinant protein via the SerAla dipeptide when the vectors for C-terminal fusion from IBA are used. Other linker sequences than SerAla lead to reduced affinity in the cases tested so far. The sequence SAWSHPQFEK fused to the N-terminal end of a recombinant protein has not been tested so far and, therefore, it is uncertain whether this equally mediates nearly irreversible binding.
Recommended buffers Binding: 25 mM Tris-HCl, 2 mM EDTA, 140 mM NaCl, pH 7.6 (optional pH 7.4-8.0)
Washing: 0.05% Tween-20 in binding buffer or PBS
Stability 6 months after shipment
Storage 4 °C
Shipment RT



Need buying or technical advice?
Contact a protein expert!
  • +49(0)551 50672-0
  • Online
  • E-mail (please indicate your complete address)



Order information
see also "how to order"

product amount cat. no. order & prices
StrepMAB-Immo coated
microplates; 96well		 1 plate 2-1521-001 online order
5 plates 2-1521-005 online order


Antigen production and detection

Versatile, Economic and High Purity production of Antigens
The Strep-tag®/ Strep-Tactin® system provides a platform for rapid and cost effective as well as versatile production and use of recombinantly produced antigens.

The Strep-tag

  • Just 8 amino acids
  • Balanced amino acid composition-generally no effect on protein structure or activity
  • Highly selective and easy binding properties
  • C- or N-terminal fusion
  • Removal not required

The technology

  • Efficient and versatile expression vectors with standardized cloning strategy
  • Affinity chromatography under physiological conditions
  • Column regeneration and activity status is visualized by color change
  • Over 99% purity can be achieved


Easy detection of Antigens

  • StrepMAB-Classic for highly selective Western blot analysis
  • Strep-Tactin AP or HRP conjugates for fast Western blot analysis



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