CaptureSelect Conjugated Ligands

Conventional antibodies, such as immunoglobin G (IgG), are composed of a heavy chain and a light chain. In some species, the IgGs lack the light chain and are composed solely of the heavy chain, yielding a heavy-chain IgG (hc-IgG). CaptureSelect affinity ligands are created by a proprietary technology based on recombinant single domain antibodies. The ligand is a ~14 kDa single domain fragment (V_HH) containing the three complementary determining regions (CDRs) that form the antigen binding domain (Figure 1).

To generate the V_HH ligand, the heavy-chain antibodies are pared down to focus on only those parts that are important for binding an antigen, which includes the CDR. The V_HH ligands maintain high affinity and specific antigen binding while being one-tenth the size of traditional antibodies. The V_HH ligands are recombinantly expressed in the yeast Saccharomyces cerevisiae in a production process free of any animal components (Animal Origin-Free).

Figure 1. A regular antibody (IgG) compared to a heavy-chain antibody (hc-Ig) lacking the light chains. CaptureSelect ligands are based on the single domain fragment (V_HH) from these hc-IgGs. On the right side, a ribbon diagram of a V_HH ligand is shown. The CDRs are indicated in red, green, and blue.

We have created an extensive list of ligands directed against:

CaptureSelect Biotin Anti-C-tag Conjugate consists of a 13 kDa V_HH affinity ligand with high affinity and selectivity for the 4-amino-acid 'C-tag' peptide tag E‐P‐E‐A (glutamic acid-proline-glutamic acid-alanine).

The Anti-C-tag affinity ligand recognizes the E-P-E-A peptide when this tag is fused directly to the C-terminus of a protein. The affinity ligand—constructed as a mono-specific bihead—is chemically conjugated to its specific label via an appropriate spacer that retains the binding reactivity of the ligand.

CaptureSelect Anti-AAVX Conjugate consists of a 14 kDA V_HH affinity ligand. The fragment specifically binds with high affinity to adeno-associated virus particles (AAV). It demonstrates good binding reactivity towards a variety of AAV serotypes, including AAV1 to AAV8, and AAVrh10. The AAVX ligand is available with different labels, such as biotin, HRP, and Alexa Fluor 647. The biotinylated and HRP-conjugated ligands can be used to develop an AAV total capsid ELISA, to quantify the total number of capsids in an AAV culture or during the production and purification process.

The Human IgG-Fc PK Biotin Conjugate consists of a 13 kDa recombinant V_HH affinity ligand, chemically conjugated to biotin. The ligand specifically binds to the Fc part of all four human IgG subclasses. The conjugate can be used for the detection, quantification, and characterization of all human (recombinant) IgG antibodies and Fc-fusion proteins in, for example, non-human plasma and/or serum samples like mouse, rat, rhesus, and cynomolgus monkey. This makes the conjugate very suitable for setting up pharmacokinetics (PK) assays.

CaptureSelect human kinetics biotin conjugates are bi-functional ligand constructs consisting of two different recombinant V_HH affinity ligands. These conjugates enable high-affinity capture of Human IgG Fab fragments that contain a kappa or lambda light chain. The bi-functional ligands are chemically conjugated to biotin, which allows immobilization on streptavidin-functionalized surfaces. They can be used for the screening of biomolecular interactions between Fab fragments and their specific target antigen. The kinetics ligands bind the CL-kappa or CL-lambda (light chain) and the CH1 domain (heavy chain) of a human IgG Fab fragment simultaneously. This binding results in extreme low dissociation rates (Kd) between the ligand and the captured Fab fragment.

CaptureSelect conjugated ligands for exosomes

CaptureSelect Biotin and HRP exosome conjugates bind with high affinity and selectivity toward the tetraspanin markers (CD81/CD63 and CD9) expressed on extracellular vesicles (EVs) like exosomes.

Applications for these include sandwich ELISA, Gyrolab™-based immunoassays, immunoprecipitation, sample prep purification using streptavidin-coupled Dynabeads or MSIA Streptavidin D.A.R.T.’S and label-free detection platforms such as those based on surface plasmon resonance (SPR) and bio-layer interferometry (BLI).

For Research Use or further manufacturing, not for diagnostic use or direct administration in humans or animals.