IgG1 Fc Fragment from Human Myeloma Plasma: Uses & Properties
IgG1 Fc Fragment from Human Myeloma Plasma: Uses & Properties
Immunoglobulin G1 (IgG1), FC Fragment from Human Myeloma Plasma is a highly purified Fc region derived from human IgG1 isolated from myeloma plasma, widely used as a biochemical tool in immunology research, Fc receptor binding studies, and as a reference standard for antibody engineering applications.
- Product SKU
- np001063
- Source Material
- Human myeloma plasma (Athens Research source: 16-16-090707-1M-FC)
- Fragment Type
- Fc fragment of IgG1 heavy chain constant region (CH2–CH3 domains)
- Immunoglobulin Class
- IgG1 (human)
- Primary Applications
- Fc receptor binding assays, isotype controls, complement activation studies, antibody engineering reference
- Storage Recommendation
- Follow supplier-specified conditions; typically -20°C for long-term storage (verify with datasheet)
What Is the IgG1 Fc Fragment and Where Does It Come From?
Immunoglobulin G1 (IgG1) is the most abundant IgG subclass in human serum and plays a central role in humoral immunity. The Fc (fragment crystallizable) region comprises the CH2 and CH3 constant domains of the IgG heavy chains and is responsible for effector functions, including binding to Fc gamma receptors (FcγRs) on immune cells and activating the classical complement pathway via C1q.
The IgG1 Fc Fragment offered by Aladdin Scientific (SKU: np001063) is isolated from human myeloma plasma, a well-established source of homogeneous, monoclonal immunoglobulin material. The myeloma origin ensures high lot-to-lot consistency and a defined glycosylation profile representative of naturally occurring human IgG1. The product is referenced to Athens Research source material (catalog reference 16-16-090707-1M-FC), providing traceability for quality assurance purposes.
Because the Fc fragment is separated from the antigen-binding Fab region, it retains all effector-function-related structural features without the confounding variable of antigen specificity, making it an ideal biochemical tool for mechanistic studies.
Key Structural and Biochemical Properties
The Fc fragment of human IgG1 exhibits several important structural and biochemical properties that researchers should understand when designing experiments:
- Domain composition: The Fc consists of two identical heavy-chain polypeptides (each containing CH2 and CH3 domains) held together by non-covalent interactions and typically one or more disulfide bonds in the hinge-proximal region.
- Molecular weight: The IgG1 Fc fragment has an approximate molecular weight of 50 kDa as a dimer (verify exact value on the product datasheet, as glycosylation contributes variability).
- Glycosylation: A conserved N-linked glycosylation site at Asn297 (EU numbering) in the CH2 domain is present in human IgG1 Fc. Myeloma-derived material retains native human glycoforms, which are critical for FcγR and C1q binding affinity.
- Fc receptor binding: Human IgG1 Fc binds with high affinity to activating receptors FcγRI (CD64), FcγRIIIa (CD16a), and to a lesser extent FcγRIIa (CD32a), enabling opsonization and ADCC assay model experiments.
- Complement activation: IgG1 Fc activates the classical complement pathway through C1q binding, supporting complement-dependent cytotoxicity (CDC) mechanistic research.
Researchers should consult the current product datasheet for lot-specific purity, concentration, and formulation details.
Research Applications
The IgG1 Fc Fragment from Human Myeloma Plasma is a versatile reagent applicable across multiple research domains:
- Fc receptor binding and competition assays: Used to characterize FcγR isoforms, map binding epitopes, and develop competitive inhibition assays. The natural glycosylation of myeloma-derived Fc makes it preferable to recombinant Fc produced in non-human expression systems for these studies.
- Isotype control and blocking reagent: Employed to block non-specific Fc receptor-mediated binding in immunoassays (ELISA, flow cytometry, immunofluorescence), reducing background and improving assay specificity.
- Complement pathway research: Serves as a defined substrate to study C1q binding, C1 complex assembly, and downstream complement activation steps without the complexity of intact antibody.
- Antibody engineering and biopharmaceutical development: Provides a human IgG1 Fc reference standard for benchmarking Fc-fusion proteins, Fc-engineered antibodies, and biosimilar development programs.
- Structural biology: Used in crystallography and cryo-EM studies of Fc–FcγR or Fc–FcRn complexes as a structurally well-characterized fragment derived from human plasma.
Always validate the suitability of each lot for your specific application by running appropriate controls.
Handling, Storage, and Quality Considerations
Proper handling and storage of the IgG1 Fc Fragment are essential to maintaining biological activity and experimental reproducibility:
- Storage temperature: For long-term storage, -20°C is typically recommended for lyophilized or concentrated protein preparations. Avoid repeated freeze-thaw cycles, which can cause aggregation and loss of structural integrity. Refer to the product datasheet for the exact recommended conditions for this lot.
- Reconstitution: If supplied in lyophilized form, reconstitute in the buffer specified on the datasheet, allow to equilibrate at room temperature briefly, and mix gently without vortexing.
- Protein aggregation: Monitor for aggregation by size-exclusion chromatography or dynamic light scattering if precise monomeric Fc is required. Aggregated Fc can cross-link Fc receptors and confound assay results.
- Endotoxin levels: For cell-based assays, verify that endotoxin levels are within acceptable limits (typically <1 EU/mg) to avoid non-specific inflammatory responses.
- Lot traceability: This product references Athens Research source material (16-16-090707-1M-FC). Retain lot number documentation for regulatory and reproducibility records.
Always consult the Safety Data Sheet (SDS) and the current product datasheet prior to use.
Frequently asked questions
What is the difference between the IgG1 Fc fragment and intact IgG1?
Intact IgG1 consists of two Fab fragments (which bind antigen) joined to the Fc region via the hinge. The isolated Fc fragment lacks the Fab regions entirely, meaning it cannot bind antigen but fully retains all Fc-mediated effector functions, including FcγR binding and complement activation. This makes the Fc fragment ideal for studies specifically targeting Fc biology without the confounding variable of antigen binding.
Why is myeloma plasma preferred as a source for IgG1 Fc fragments?
Myeloma plasma provides a monoclonal source of immunoglobulin, ensuring high homogeneity and lot-to-lot consistency compared to polyclonal serum-derived IgG. Additionally, myeloma-derived material retains authentic human glycosylation patterns at Asn297, which are critical for Fc receptor and complement interactions. Recombinant Fc produced in non-human cell lines may carry non-human glycoforms that can alter binding properties.
Can the IgG1 Fc fragment be used as a blocking reagent in immunoassays?
Yes, the IgG1 Fc fragment is commonly used to block non-specific Fc receptor-mediated binding in immunoassays such as flow cytometry and immunofluorescence, particularly when using Fc-containing detection antibodies on cells that express FcγRs. The Fc fragment saturates available Fc receptors, reducing background staining. Optimal blocking concentration and incubation conditions should be determined empirically for each experimental system.
How should I verify the integrity of the IgG1 Fc fragment upon receipt?
Upon receipt, inspect the vial for physical integrity and confirm storage conditions during transit. Recommended quality checks include SDS-PAGE under reducing and non-reducing conditions to confirm molecular weight and purity, and size-exclusion HPLC or DLS to assess aggregation state. Functional verification can be performed using an Fc receptor binding ELISA or SPR if critical for your application. Always compare results against the certificate of analysis provided with the lot.
References
- Janeway CA Jr, et al. Immunobiology: The Immune System in Health and Disease. 5th ed. New York: Garland Science; 2001. Chapter on antibody structure and function.
- Jefferis R. Glycosylation as a strategy to improve antibody-based therapeutics. Nat Rev Drug Discov. 2009;8(3):226-234. doi:10.1038/nrd2804
- Bruhns P, et al. Specificity and affinity of human Fc gamma receptors and their polymorphic variants for human IgG subclasses. Blood. 2009;113(16):3716-3725. doi:10.1182/blood-2008-09-179754
Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.
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