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General PK assay antibodies for scFv, BsAb, etc. (including G4S linker)
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Last year, Hycells launched its blockbuster, universal CAR positivity assay antibody—Anti-G4S linker—which quickly won widespread recognition and collaboration from a growing customer base thanks to its ease of use and high precision. Anti-G4S linker is a universally applicable CAR positivity assay reagent that has been rigorously validated by numerous customers; by eliminating unnecessary and time-consuming steps, it accelerates the drug development process. It is suitable for detecting CARs with G4S linkers targeting any antigen ((G4S)n, where n ≥ 2), as well as for assays of various antibody types that incorporate (G4S)n, where n ≥ 2. Moreover, it exhibits robust resistance to interference, remaining unaffected by antigen cross-reactivity and delivering more accurate in vivo CAR proportion measurements. Its exceptional sensitivity ensures outstanding detection performance even at very high or very low concentrations.
Building on the successful development of the Anti-G4S linker product and the positive feedback from customer applications, Hycells has leveraged its existing technology service platform to innovate and expand into diverse application scenarios, further developing the new G4S-HRP product. Dedicated to the service of fusion proteins, single-chain antibodies (scFv), and other molecules bearing a linker (G4S) n structure. Bispecific antibody drugs A research and development platform that provides antibodies—critical tools for screening, detection, and target-based research.
Item number Product Name Specifications GS-ARHR20 Anti-(G4S)n (B02H1)mAb(HRP) 20 μL GS-ARHR100 Anti-(G4S)n (B02H1)mAb(HRP) 100 μL GS-ARHR200 Anti-(G4S)n (B02H1)mAb(HRP) 200 μL GS-ARHR1000 Anti-(G4S)n (B02H1)mAb(HRP) 1ml Specificity: This product is specific for scFvs in different species (humanized, mouse) and different orders (VH-linker-VL, VL-linker-VH). It can also recognize various forms of scFv-based bispecific antibodies, such as DART, BiTE, TandAbs, IgG(H)-scFv2, scFv-Fab-Fc, etc.
Host Species: Rabbit
Conjugate: Horseradish peroxidase (HRP)
Concentration: 0.5 mg/mL
Storage Instructions: Store at 2–8°C and protect from prolonged exposure to light. This product is stable for 1 year upon receipt when handled and stored as instructed.
Purification: Protein A affinity column
Isotype: Rabbit IgG1
Clonality: Monoclonal antibody cocktail
Background on the Flexible Linker (G4S)n
01/ Single-chain antibody (scFv)
A complete antibody consists of two heavy chains (H) and two light chains (L); through genetic engineering, it can be modified to express only the variable regions, which are then linked via a synthetically engineered linker peptide gene. Antibody heavy chain variable region The variable region of the heavy chain (VH) and the variable region of the light chain (VL) can be linked to form a recombinant gene; the antibody expressed from this recombinant gene is referred to as a single-chain variable fragment (scFv). Structurally, the N-terminus of the heavy chain can be joined to the C-terminus of the light chain, or vice versa. The linker typically consists of 15–25 amino acids, usually composed of glycine (Gly) and serine (Ser), in the sequence (G4S)n, which confers both flexibility and protease resistance. The primary function of the linker is to connect VH and VL while maintaining sufficient elasticity, ensuring that even after the functional domains of VH and VL have folded, they can still pair up to form a monovalent antigen-binding site. scFvs possess several advantageous properties, including small molecular size, strong tissue penetration, and high specificity. They play a crucial role in targeted therapy, medical imaging diagnostics, and biosensing. Importantly, in the field of cell therapy, scFvs can serve as the antigen-recognition domain of CAR-T cells, thereby determining the targeting capability of these cells.
Through analysis of natural multi-domain protein linkers, researchers have identified numerous candidate linkers suitable for protein fusion. In addition, many empirically designed linkers with diverse sequences and conformations have been created for the construction of recombinant fusion proteins. Currently, commonly used classical linkers can be classified into three categories: flexible linkers, rigid linkers, and cleavable linkers.
Taking Eli Lilly’s blockbuster drug, the FC-fusion protein dulaglutide, as an example, it consists of two Glucagon-like peptide-1 The (GLP-1) molecule is conjugated to the Fc region of human IgG4 via a flexible G4S)n linker, thereby preventing drug inactivation that would otherwise result from fusion with the Fc region.
Among them, the most commonly used flexible linkers are primarily composed of Gly and Ser, namely the (G4S)n linker. By adjusting the value of n, the linker length can be optimized to achieve appropriate separation of protein functional domains or to maintain essential interdomain interactions.
Take the BiTE-format bispecific antibody as an example: Amgen’s BiTE bispecific antibody technology platform is a format developed by Micromet (which was later acquired by Amgen), in which two single-chain antibodies are linked together via a (G4S)n linker, with each single-chain antibody capable of recognizing a distinct antigen. A bispecific BiTE antibody targeting both CD19 and CD3 has the following structural configuration:
In summary, the G4S HRP product is suitable for PK and WB assays of single-chain antibodies (scFVs), fusion proteins, and bispecific antibody drugs that contain the (G4S)n linker structure, serving as an important antibody tool for screening, detection, and targeted research.
G4S HRP Product Advantages:
No.1
High applicability
No.2
High affinity
No.3
High sensitivity
No.4
High batch-to-batch stability
No.5
Non-specific signal
Sample EC50 (μg/mL) Top Ab1-Hycells 0.5461 2.783 Ab2-Hycells 0.06573 3.147 G4S HRP—PK Application Testing
Anti-human Fc mAb system
Sample EC50 (μg/mL) Top Ab1-Casein 0.5461 2.783 Ab1-Monkey Plasma 0.5328 2.923 Sample EC50 (μg/mL) Top Ab2-Casein 0.06169 2.725 Ab2-Monkey Plasma 0.1182 2.794 Conclusion: A universal assay system that uses anti-human Fc antibody-coated beads to capture the target antibodies in serum is suitable for PK analysis of target antibodies in monkey serum.
Antigen system
Sample EC50 (μg/mL) Top Ab2-Casein 0.06415 2.545 Ab2-Human Plasma 0.05497 2.624 Ab2-Monkey Plasma 0.06468 2.655 Conclusion: The system in which capture antigen is used to immobilize the antibody of interest in serum is suitable for PK assays of the antibody of interest in human or monkey serum.
For more details on HeYouSheng Bio’s G4S-HRP products, please contact our sales representative. You can also scan the QR code below to request a sample kit. Contact: Mr. Xie, 15201775322.
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Download of documentation related to universal PK assay antibodies for scFv, BsAb, etc. (including the G4S linker):
Related document downloads:
G4S-ARHR200 Instruction Manual
G4S-ARHR100 Instruction Manual
G4S-ARHR20 Instruction Manual
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