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The Avi-Tag Site-Specifically Biotinylated Antigen Family provides recombinant antigens that carry exactly one biotin moiety per molecule, installed at a single, predefined position through BirA-mediated enzymatic labeling of the Avi-tag sequence (GLNDIFEAQKIEWHE). Unlike conventional chemical biotinylation, which modifies multiple lysine residues at random and produces heterogeneous conjugates, enzymatic Avi-tag biotinylation yields a homogeneous, structurally defined product in which the label is spatially separated from functional epitopes and binding domains.
This family covers more than 130 antigens across five research areas: infectious diseases, autoimmune biomarkers, allergens, cancer biomarkers, and cardiovascular biomarkers. Each antigen is produced under controlled expression and labeling conditions to ensure defined biotinylation efficiency, high biological activity, and robust batch-to-batch reproducibility, supporting reliable performance in ELISA, chemiluminescent immunoassays, lateral flow research assays, flow cytometry, surface plasmon resonance (SPR), and bio-layer interferometry (BLI).
The biotin-streptavidin interaction is one of the strongest non-covalent interactions known (Ka approximately 10^15 M-1) and is the backbone of countless immunoassay and biosensor formats. However, the value of this system in assay development depends heavily on how the biotin is attached to the antigen. Random chemical labeling creates a mixture of species with different degrees of labeling and different modification sites. This heterogeneity can mask critical epitopes, reduce binding activity, and introduce lot-to-lot variability that complicates assay development and transfer.
Avi-tag biotinylation eliminates these variables. The Avi-tag is fused genetically to the N- or C-terminus of the recombinant antigen, and purified BirA ligase catalyzes the transfer of a single biotin to one specific lysine residue within the tag. Excess biotin and enzyme are removed during purification, yielding a uniform, mono-biotinylated antigen with preserved native structure and full epitope accessibility.
Fig. 1. Principles of Avi-tag site-specific biotinylation
The Avi-tag biotinylated antigen family is built around the target classes that matter most in current immunoassay and antibody research. The following classes illustrate where we have focused our development efforts and how these antigens are used in research.
Autoimmune biomarkers are a core focus of this family. Zinc transporter 8 (ZnT8) is a major autoimmune research target in type 1 diabetes studies, where anti-ZnT8 antibodies complement GADA, IA-2A, and IAA in autoimmune marker research. The histone H2A/H2B dimer is a key autoantigen in systemic lupus erythematosus and drug-induced autoimmunity research. Site-specifically biotinylated formats of these targets support oriented capture on streptavidin surfaces for autoantibody research assays.
Infectious disease targets span viral and bacterial antigens used in serology research. Hepatitis B virus core antigen (HBcAg) is a widely used target in hepatitis B research immunoassays. The dengue virus NS1 antigens from all four serotypes (DENV-1 to DENV-4) address flavivirus serology research, and rubella virus glycoprotein E1 supports rubella antibody research. These targets extend the same single-site labeling standard to high-priority infectious disease research areas.
Recombinant allergens such as the major birch pollen allergen Bet v 1 are essential raw materials for allergy research, including allergen-specific IgE research assays and component-resolved allergy studies. Avi-tag biotinylation preserves allergen conformation and IgE-binding epitopes while enabling plug-and-play use in streptavidin-based research formats.
Representative products from these target classes are validated for ELISA, CLIA, and flow cytometry applications, demonstrating that single-site biotinylation preserves antibody-recognition performance across multiple research assay formats.
Biotinylated antigens can be captured in a controlled orientation on streptavidin-coated solid phases, supporting sensitive and reproducible ELISA, CLIA, and lateral flow research assay development in infectious disease serology, autoimmune marker, and allergen-specific antibody studies.
Site-specific biotinylation ensures consistent epitope exposure across screening campaigns, improving comparability in hybridoma screening, phage display biopanning, and antibody affinity ranking by ELISA, flow cytometry, SPR, and BLI.
Oriented immobilization on streptavidin biosensor surfaces enables accurate measurement of binding affinity, kinetics, and specificity for antigen-antibody and protein-ligand interactions.
The defined single-label format makes these antigens well suited as reference reagents for assay calibration, lot comparison, and long-term stability monitoring in research settings.
| Cat. No. | Product Name | |
| DAG-WT3500 | Biotinylated Recombinant Human ApoE3 Protein [His, Avi] | Inquiry |
| DAG-WT6921B | Biotinylated Recombinant BNP [hFc, Avi] | Inquiry |
| DAG-WT6922B | Biotinylated Recombinant NT-proBNP [hFc, Avi] | Inquiry |
| DAG-WT6923B | Biotinylated Recombinant Troponin I [His, Avi] | Inquiry |
| DAG-WT6924B | Biotinylated Recombinant Troponin T [His, Avi] | Inquiry |
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