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| Product Name | Protein G Magnetic Beads |
| Catalog No. | MAGBEA-0011 |
| Description | Protein G-functionalized superparamagnetic beads for the high-affinity purification of IgG antibodies across a broad range of species and subclasses. Recombinant Protein G, engineered to remove the albumin-binding domain while retaining the IgG-binding domains, is covalently coupled to the bead surface. Protein G provides superior binding to many IgG subclasses that bind weakly to Protein A, including mouse IgG1, rat IgG, human IgG3, and ruminant IgGs, making these beads an essential tool for laboratories working with diverse antibody sources. |
| Intended Use | Purification of monoclonal and polyclonal IgG antibodies from cell culture supernatant, serum, plasma, and ascites, particularly from species and subclasses with weak Protein A affinity including mouse IgG1, rat IgG, human IgG3, sheep, and goat antibodies. |
| Principle / Technology | Recombinant engineered Protein G (approximately 22 kDa, containing two IgG-binding domains C1 and C2, with albumin-binding domain genetically deleted) is covalently linked to the bead surface through oriented C-terminal coupling chemistry. The exposed IgG-binding domains recognize the CH2-CH3 interface of the Fc region with high affinity across a broad species range and pH range. IgG is captured at near-neutral pH, contaminants are removed by washing, and purified IgG is eluted at mildly acidic pH. The elimination of the albumin-binding domain ensures no significant co-purification of serum albumin. |
| Detection Method | DLS for size; BCA for Protein G density; IgG binding isotherm by UV280; SDS-PAGE and SEC-HPLC for IgG purity; ELISA-based IgG subclass binding panel; Protein G leaching ELISA; endotoxin; bead stability under repeated use |
| Sample Type | Monoclonal and polyclonal IgG from: mouse (all subclasses including IgG1), human (all subclasses including IgG3), rat (IgG1, IgG2a, IgG2b), rabbit, goat, sheep, bovine, horse, guinea pig; cell culture supernatant, serum, plasma, ascites fluid; species preference differs from Protein A—refer to binding specificity table for optimal selection |
| Performance Range / Specifications | Particle diameter: 1-2 µm; Protein G density: 3-10 mg/mL settled beads; IgG binding capacity: 15-30 mg human IgG/mL settled beads; dynamic binding: 10-25 mg/mL (10-min residence); albumin binding: <0.5 mg BSA/mL (negligible due to domain deletion); non-specific binding: <3% of total protein; IgG purity: >95% by SDS-PAGE; Protein G leaching: <5 ng/mg IgG; magnetic separation: <10 seconds |
| Sensitivity / LOD | Effective IgG purification from solutions with antibody concentration as low as 5 µg/mL; microgram-scale purification reproducible with small bead volumes; IgG recovery >80% from dilute cell culture supernatant; detection of purified IgG from single hybridoma well supernatant |
| Specificity | High-affinity binding to IgG across broad species range; specificity for Fc region (no Fab binding); no albumin binding (engineered deletion of albumin-binding domain); no cross-reactivity with IgM, IgA, IgE, or IgD; host cell protein reduction >98% from cell culture harvest; purified IgG free of albumin, transferrin, and other serum/medium proteins |
| Reaction Conditions / Protocol | Wash beads with binding buffer (PBS pH 7.4 or sodium acetate pH 5.0 for optimal binding); incubate with antibody-containing sample for 10-30 minutes at room temperature with continuous rotation; magnetically separate; wash beads 3-4 times with binding buffer; elute bound IgG with 0.1 M glycine-HCl pH 2.5-3.0; incubate 2-5 minutes; separate beads; immediately neutralize eluate with 1 M Tris-HCl pH 9.0 (1/10 volume); total time: 30-60 minutes; beads can be regenerated 5-10 times |
| Components / Formulation | Protein G-coated superparamagnetic beads, 25-50% slurry in 20% ethanol or PBS pH 7.4 with 0.02% sodium azide; recombinant Protein G (C1-C2 domains, albumin-binding domain deleted) expressed in E. coli; binding, wash, and elution buffers not included |
| Storage Conditions | 2-8°C in 20% ethanol (recommended for long-term) or PBS with sodium azide; do not freeze; protect from light; Protein G is less alkali-stable than Protein A—limit NaOH exposure; use aseptic technique to prevent microbial growth |
| Shelf Life | 24 months at 2-8°C in 20% ethanol; 12 months in PBS/azide at 2-8°C; Protein G activity >85% retained at 24 months; accelerated stability at 37°C supports claimed shelf life; opened product: use within 6 months |
| Package Specifications | 1 mL, 5 mL, 10 mL 25-50% slurry; pre-packed spin columns available; bulk and OEM packaging; trial packs for evaluation; supplied in secure-cap vials or bottles |
| Product Form | Dark brown suspension in preservative-containing storage buffer; homogeneous after gentle mixing; rapid bead settling; clear supernatant after magnetic separation; no visible bacterial or fungal growth; uniform appearance across lots |
| Quality Control | Per lot: Protein G density, IgG binding capacity (polyclonal human and mouse IgG), species subclass binding panel (ELISA), albumin binding (BSA test), IgG purity, Protein G leaching, endotoxin, sterility, particle size, magnetic responsiveness; functional test with mouse IgG1 hybridoma supernatant |
| Key Features | Albumin-binding domain genetically deleted for pure IgG isolation; broad species and subclass reactivity complementing Protein A; high binding capacity; low ligand leaching; engineered alkaline stability improvement over wild-type Protein G; magnetic bead format for batch processing convenience; validated for mouse IgG1 (weak Protein A binder) purification |
| Purity | Protein G >95% by SDS-PAGE; no protease activity; IgG purity >95% by SDS-PAGE and SEC-HPLC; endotoxin <0.1 EU/mg; residual albumin in eluate <0.1% of total protein; host cell protein in eluted IgG <500 ppm |
| Concentration | 25-50% slurry; Protein G density 3-10 mg/mL settled beads; IgG binding capacity 15-30 mg/mL settled beads; exact values per lot certificate; bead count per mL available upon request |
| Activity / Unit Definition | Human IgG binding: 15-30 mg/mL settled beads; mouse IgG binding: 10-20 mg/mL (subclass-dependent); binding constant (Kd): ~10^-8 to 10^-9 M; >90% activity retained through 5-10 regeneration cycles; no significant albumin binding (<0.1 mg BSA/mL) |
| Molecular Weight | Recombinant Protein G: ~22 kDa (C1-C2 domains only, albumin-binding domain deleted); native Protein G: ~65 kDa (includes albumin-binding domain, not used); bead molecular weight not defined |
| Source / Origin | Recombinant Protein G engineered from Streptococcus sp. Group G gene, expressed in E. coli; C1 and C2 IgG-binding domains retained; albumin-binding domain (A domain) genetically deleted; magnetic beads are synthetic polymer-magnetite composite; no animal-derived components; no Streptococcal culture used in manufacturing |
| pH Range / Optimal pH | IgG binding: pH 5.0-8.0 (broader than Protein A; optimal 5.0-7.0 for many species); elution: pH 2.5-3.0; bead stability: pH 2-11; Protein G is less alkali-tolerant than Protein A—avoid prolonged exposure to pH >11; 0.1 M NaOH exposure limited to 5-10 minutes for cleaning |
| Shipping Conditions | Ambient temperature in 20% ethanol; cold packs optional; do not freeze; ethanol-based formulation requires flammable liquid shipping compliance for air freight; PBS/azide formulation: non-hazardous, ambient or cold pack shipping |
| Expiration Date / Stability | 24 months in 20% ethanol at 2-8°C; 12 months in PBS/azide; real-time stability confirmed by IgG binding capacity and leaching monitoring; Protein G biological activity maintained; ethanol concentration remains within specification through expiry; sodium azide preservative efficacy verified |
| Regulatory / Compliance | For research use and component manufacturing; suitable for antibody purification for preclinical studies; recombinant product; ISO 9001 manufacturing; certificate of analysis per lot; quality agreement and DMF support available for commercial supply |
| Compatibility | Compatible with PBS, Tris, HEPES binding buffers; acetate and phosphate buffers also suitable; glycine-HCl or citrate elution buffers; regeneration: 0.1 M glycine-HCl pH 2.0 stripping, followed by immediate neutralization; CIP: limited NaOH use (0.05-0.1 M, <10 minutes); avoid guanidine HCl above 3 M (may denature Protein G) |
| Recommended Buffer System | Storage: 20% ethanol in water or PBS with sodium azide; binding: PBS pH 7.4 or 20 mM sodium acetate pH 5.0; wash: binding buffer; elution: 0.1 M glycine-HCl pH 2.5-3.0; neutralization: 1 M Tris-HCl pH 9.0; cleaning: 0.1 M glycine pH 2.0 or 0.05 M NaOH |
| Application Notes / Precautions | Protein G binds mouse IgG1 strongly, unlike Protein A—choose based on antibody subclass; for human IgG3 purification, Protein G is superior to Protein A; optimal binding pH for mouse IgG1 is pH 5.0-6.0; excessive elution buffer contact (>10 minutes) should be avoided to prevent antibody aggregation; neutralize eluted IgG immediately; for low-concentration antibody samples, extend incubation time to 60 minutes; beads can be pooled into columns if preferred over batch format |
| Batch-to-Batch Consistency | Protein G density CV <15% between lots; IgG binding capacity CV <12%; species panel binding profile consistent per lot; Protein G leaching <5 ng/mg across all lots; IgG purity >95% per lot; comprehensive lot traceability documentation |
For research use only, not for clinical use.
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