S-SS-4FB Cleavable Linker

SKU Unit Size Price Qty
S-1037-010 10 mg

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S-SS-4FB is an analog of S-4FB with a cleavable disulfide group in the linker enabling intracellular cleavage of the conjugate. S-SS-4FB reacts with primary amines on proteins (through lysine amino acids), amino-modified oligonucleotides or surfaces, introducing a 4FB (4-formylbenzamide) linker that forms stable covalent conjugates with biomolecules containing HyNic linkers. Intracellularly, disulfide bonds of S-SS-4FB are cleaved by glutathione, liberating a drug payload from its carrier.


More Information
Label/Modifier Type 4FB
Reactivity HyNic
Recommended Storage None,
Applications Antibody Labeling, Antisense/RNAi, Aptamers, Immunotherapeutics
Other Name(s) Solulink Bioconjugation

Kit Components



Technical Information

Introduction to Solulink Bioconjugation Technology

SoluLINK’s core technology is based on the formation of a stable aromatic bond that has a UV-traceable signal to indicate the real-time formation of the conjugate. S-HyNic 1 (succinimidyl 6-hydrazinonicotinate acetone hydrazone, SANH) is used to incorporate aromatic hydrazine linkers on biomolecules. S-HyNic is an amino-reactive reagent that directly converts amino groups on biomolecules and surfaces to HyNic groups. S-4FB 2 (succinimidyl 4-formylbenzoate, SFB) is used to convert amino groups to aromatic aldehydes (4-formylbenzamide (4FB) groups). Addition of a HyNic-modified biomolecule to a 4FB-modified biomolecule or surface directly leads to the formation of the conjugate (Figure 1). The conjugate bond is stable to 92OC and pH 2.0-10.0. The recommended pH for antibody conjugation is 6.0. Unlike thiol-based conjugation protocols where reducing reagents are required that that can compromise the activity of proteins by cleaving disulfide bonds, the HyNic-4FB conjugation couple leaves disulfide bonds intact. No oxidants, reductants or metals are required in the preparation of conjugate.

Figure 1: Schematic representation of SoluLINK Bioconjugation chemistry where an antibody is modified with S-HyNic to incorporate HyNic groups and a second protein is modified with S-4FB to incorporate 4FB groups. Conjugate is formed directly by simply mixing the HyNic-modified antibody with the 4FB-modified proteins.

Further enhancing the many advantages of the HyNic/4FB conjugation couple is the discovery by Dirksen et al. that showed that aniline catalyzes the formation of this Schiff’s base. This is especially effective for large biomolecule conjugations. In the case of antibody-protein conjugations the addition of 10 mM TurboLink Catalyst Buffer (aniline) to the reaction mixture converts >95% of the antibody to conjugate in ~2 hours using 1-2 mole equivalents of second protein. 

The HyNic-4FB conjugation couple is chromophoric- the conjugate bond absorbs at 354 nm and has a molar extinction coefficient of 29000. This allows (1) real time spectrophotometric monitoring of a conjugate reaction, (2) ability to ‘visualize’ the conjugate during chromatographic purification using a UV or photodiode array detector and (3) quantification of conjugation.

Intellectual Property

SoluLINK Bioconjugation For Research Use Only. Not for use in diagnostic procedures. For additional licensing restrictions, please see the license agreement at vectorlabs.com/solulink-research-license.

Products are for research use only, not for use in diagnostic or therapeutic procedures or for use in humans. Products are not for resale without express written permission of Seller. No license under any patent or other intellectual property right of Seller or its licensors is granted or implied by the purchase unless otherwise provided in writing.

TriLink does not warrant that the use or sale of the products delivered hereunder will not infringe the claims of any United States or other patents or patents pending covering the use of the product alone or in combination with other products or in the operation of any process. All and any use of TriLink product is the purchaser's sole responsibility.