Buccutite™ is AAT Bioquest's proprietary bioconjugation technology for high-yield protein-protein crosslinking. Unlike traditional SMCC chemistry, which can lead to antibody instability and homo-crosslinking due to thiol reduction and maleimide side reactions, Buccutite™ uses complementary FOL and MTA reactive groups that selectively react with each other under mild, neutral conditions without catalysts. Buccutite™ kits allow optimal labeling of microgram amounts of antibodies (as little as 25 µg per labeling reaction) in less than two hours, with no purification necessary and nearly 100% recovery of conjugate.

Buccutite™ crosslinking technology offers several key advantages that make it a clear choice over older conjugation methods like SMCC. These include:

Phycobiliproteins offer exceptionally high extinction coefficients and quantum yields, making them ideal labels for flow cytometry and immunofluorescence applications where maximum sensitivity is required. Because of their protein nature and structural complexity, phycobiliproteins are not well suited for conjugation using the same small-molecule labeling chemistries applied to synthetic dyes; instead, they require protein-protein crosslinking strategies that must be carefully optimized to preserve both antibody binding function and fluorophore brightness.

AAT Bioquest's Buccutite™ antibody labeling kits provide a streamlined, reliable method for generating high-quality phycobiliprotein-antibody conjugates with consistent yields and minimal loss of fluorescence intensity.

Tandem dye labeling kits enable researchers to expand their multicolor flow cytometry panels by coupling phycobiliprotein donors (PE or APC) with small-molecule acceptor dyes that shift emission via FRET. These kits provide ready-to-use conjugation reagents for generating bright, spectrally distinct antibody conjugates optimized for modern cytometers equipped with multiple laser lines. PE tandems are excited at 565 nm with emission options typically spanning approximately 606–778 nm, while APC tandems are excited at 651 nm with emission options from 700–793 nm.

Enzyme-conjugated antibodies are essential reagents for immunoassay detection methods including ELISA, Western blotting, and immunohistochemistry, where the enzymatic activity of horseradish peroxidase (HRP) or alkaline phosphatase (ALP) generates colorimetric, chemiluminescent, or fluorescent signals for target visualization. Buccutite™ enzyme conjugation kits use a bifunctional crosslinking approach that efficiently links the detection enzyme to antibodies while preserving both antibody binding activity and enzyme catalytic function. For applications requiring maximum sensitivity with limited sample, the PolyHRP kit provides multiple HRP molecules per antibody to dramatically amplify signal output.

In addition to Buccutite™ kits for fluorophore and enzyme conjugation, kits are available for custom and application specific crosslinking. Some examples include:

For researchers who require maximum flexibility in their conjugation workflows, individual Buccutite™ reactive components are available for custom protocol development and optimization. The Buccutite™ system uses a pair of complementary crosslinkers, designated MTA and FOL, which react rapidly and specifically with each other under mild aqueous conditions to form stable covalent linkages between the two labeled biomolecules. NHS ester and maleimide forms allow selective targeting of amine or thiol groups on proteins, while scavenger reagents enable quenching of unreacted crosslinker to minimize side reactions and improve conjugate purity. Quantitation dyes (MTA-Dye 650 and FOL-Dye 650) provide a convenient spectrophotometric method for determining crosslinker incorporation efficiency prior to the final conjugation step.