Data sheets | SPR Sensor chips

Protein AG–modified sensor chips

XanTec's PAGP, PAGD, and PAGHC sensor chips are coated with a bioinert polycarboxylate matrix pre-functionalized with recombinant 50.5 kDa Protein AG. This non-glycosylated Protein AG variant includes four IgG-binding domains derived of Protein A and two IgG-binding domains from Protein G, providing high-affinity binding to the Fc region of all human IgG subclasses. Additionally, it exhibits strong affinity for mouse IgG2a, IgG2b, and IgG3, as well as total IgG from other mammals including cow, goat, sheep, and rabbit.

To ensure highly specific IgG binding, non-essential domains—such as cell wall-binding, cell membrane-binding, and albumin-binding regions—have been removed from the recombinant Protein AG. Nevertheless, due to its slightly hydrophobic character, some nonspecific binding may still occur. The inclusion of blocking agents (e.g., BSA) and/or nonionic detergents (e.g., Tween) in the running buffer is therefore recommended to minimize background signals.

XanTec’s Protein AG sensor chips are ready-to-use, eliminating the need for time-intensive assay optimization and streamlining workflows. With five distinct Protein AG-modified versions available for SPR applications, each is tailored to specific analytical needs.

Key features:

Fast assay development: No preconcentration or surface activation required. Controlled and reversible ligand immobilization is performed under physiological conditions, reducing preparation time and ensuring reproducibility.
Broad antibody compatibility: Broader antibody subclass and species affinity than Protein A.
Simple regeneration: Chip surfaces regenerated using glycine·HCl pH 1.5.
High stability: XanTec’s Protein AG sensor chips help minimize assay costs and maximize reusability.
Oriented immobilization: High ligand activity is maintained via directed immobilization through the Fc region.

Schematic illustration of a 3D PAG sensor chip. Red dots represent negatively charged carboxyl groups distributed along the green polymer chains. The decaying red gradient represents the evanescent field. The magnified view shows immobilized Protein AG binding an IgG antibody via its Fc region.¹

Product code²	PAGP	PAGD200L	PAGHC30M	PAGHC200M
Base coating	2D, ultra-short bioinert CM-dextran (high density)	3D, 200 nm bioinert CM-dextran (low density)	3D, 30 nm bioinert polycarboxylate (medium density)	3D, 200 nm bioinert polycarboxylate (medium density)
Capture immobilization capacity [µRIU]³	≈ 5,000	≈ 12,000	≈ 6,000	≈ 11,000
Ligands	Fc region of all human IgG subclasses, strong affinity for mouse IgG2a, IgG2b, and IgG3, and total IgG from cow, goat, sheep, and rabbit
Analytes	proteins peptides nucleic acids	proteins peptides nucleic acids small molecules	proteins peptides nucleic acids carbohydrates	proteins peptides nucleic acids carbohydrates small molecules
Intended purpose	kinetic measurements based on oriented Fc-region immobilization capture immobilization of Fc fusion proteins and antibodies for analysis of medium- to large-sized analytes	capture immobilization of Fc fusion proteins and antibodies for analysis of small- to medium-sized analytes antibody quantification	capture immobilization of Fc fusion proteins and antibodies for analysis of medium- to large-sized analytes including carbohydrates	capture immobilization of Fc fusion proteins and antibodies for analysis of small- to medium-sized analytes including carbohydrates antibody quantification

¹ All illustrations are schematic representations and are not drawn to scale; dimensions, densities, and spatial relationships do not reflect actual physical or chemical proportions.

² Table includes a selection from XanTec’s full Protein AG sensor chip portfolio.

³ Based on specific binding of 100 µg/mL IgG in phosphate-buffered saline (PBS), with 1 µRIU corresponding approximately to 1 RU.

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Protein AG–modified sensor chips