Monobiotinylated recombinant proteins

In Rekom Biotech we have developed a product line of monobiotinylated proteins, offering some of our catalog numbers with a biotin in their C-terminus. This molecule allows the specific interaction of biotinylated proteins to streptavidin.

Our biotinylated proteins are bonded to a BCCP-tag in the C-terminus, with a lysine residue which is enzymatically biotinylated by the E. coli biotin ligase BirA. This single-point labelling technique has many advantages for commonly used binding assays:

  • The biotinylation only happens on the lysine residue of the BCCP tag.
  • There is NO interference with the target protein’s natural binding activities.
  • The protein orientation is uniform when immobilized on a streptavidin-coated surface such as nanoparticles.

Take a look at our monobiotinylated proteins and do not hesitate to contact us if you need anything.


Acquired immunodeficiency syndrome (AIDS) / Human immunodeficiency virus (HIV)

RAG0057BIOT (biotinylated)
Viral capsid antigen

Babesiosis (or piroplasmosis)

RAG0020BIOT (B. canis, biotinylated)
Merozoite Surface Antigen

Chagas / Trypanosoma cruzi

RAG0096BIOT (biotinylated, chimera)
Multi-epitope recombinant chimeric antigen for Chagas

Cytomegalovirus infection (CMV)

RAG0109BIOT (biotinylated, chimera)
Multi-epitope recombinant chimeric antigen for CMV
RAG0110BIOT (biotinylated, chimera)
Multi-epitope recombinant chimeric antigen for CMV
RAG0090BIOT (biotinylated)
DNA polymerase processivity subunit

Epstein-Barr virus infection (EBV)

RAG0049BIOT (biotinylated)
Viral capsid antigen

Leishmaniasis / Leishmania infantum

RAG0061BIOT (biotinylated)
Parasite kinesin-related antigen

Neosporosis / Neospora caninum

RAG0024BIOT (biotinylated)
Dense granule antigen GRA7

Oral herpes / Herpes simplex virus type 1 (HSV-1)

RAG0017BIOT (biotinylated) New
Mature glycoprotein G (gG-1)

Phleum pratense (Timothy grass pollen)

Phl p 5a
RAL0003BIOT (biotinylated)

Syphilis / Treponema pallidum

RAG0046BIOT (biotinylated, chimera)
Multi-epitope recombinant chimeric antigen for Treponema pallidum
RAG0064BIOT (biotinylated, chimera)
Multi-epitope recombinant chimeric antigen for Treponema pallidum
RAG0009BIOT (biotinylated)
Membrane lipoprotein
RAG0008BIOT (biotinylated)
Membrane lipoprotein
RAG0010BIOT (biotinylated)
Membrane lipoprotein

Triticum aestivum (Wheat)

Tri a 19
RAL0053BIOT (biotinylated)
Omega-5 gliadin, seed storage protein

Conventional chemical conjugation

Monobiotinylated protein
Figure 1. Monobiotinylated protein

A conjugated antigen can be a helpful solution for various issues that can arise during the development of a new IVD test. One common problem caused by most surfaces is the denaturation of proteins due to their high surface hydrophobicity.

Furthermore, the binding events may be affected by the position of the surface and sensor molecules, which could cause a greater steric impact. Moreover, positioning the molecules in a specific orientation could enhance the stability of the attached proteins and make the assay more sensitive by exposing its antigenic regions.

Traditional methods of conjugation are effective for antibodies, but they may not provide consistent results for antigens with less established structures. This may explain why Double-Antigen Sandwich ELISAs (DAgS) are not as widely used for detecting antibodies compared to indirect ELISA.

To avoid compromising the antigenic structure and sensitivity of DAS-ELISAs due to conventional chemical conjugation, the ideal solution is to utilize monobiotinylated proteins.

Why use our monobiotinylated proteins?

The extremely specific and high affinity binding of biotin by avidin and/or streptavidin (Kd ≈ 10-14M) results in specific detection systems of very high sensitivity. A clear advantage of this system is that with a common strep-HRP, we can obtain conjugated complex of all our references without the necessity of performing the peroxidation of each one.

The biotin is fused to a linker which maintains the molecule away to the protein surface, avoiding steric hindrance between the biotin and the antigenic regions involved in Ab-binding. Thus, the Ab interaction will not be compromised with the conjugation.

Interaction between an antigen vs Fab region of an Ab
Figure 2. 3D image showing an antigen (green) interacting with the specific Fab region of the Ab (pink). The image also highlights certain amino acids (red) that are typically involved in conjugation procedures. It's important to note that some of these amino acids are part of the epitope region of the protein. If conjugation were to occur with these amino acids, it could interfere with the Ab-binding process and ultimately decrease the antigenic capacity of the protein.

As there is just one biotin per protein molecule, our conjugated proteins will show a higher inter-lot reproducibility and this will facilitate the reproducibility of the diagnostic tests developed with them.

Monobiotinylated proteins applications

Protein orientation in streptavidin-coated plates
Protein orientation in streptavidin-coated plates
Detection in IgM capture assays
Detection in IgM capture assays
Detection in DAS assays
Detection in DAS assays
Binding to gold and other nanoparticles coated with streptavidin
Binding to gold and other nanoparticles coated with streptavidin