aprN Antibody
Description
Antibody Structure and Function
Antibodies (immunoglobulins) are Y-shaped proteins composed of four polypeptide chains: two identical heavy chains (~50 kDa each) and two identical light chains (~25 kDa each) . These chains are linked via disulfide bonds, forming two antigen-binding sites (Fabs) and a constant region (Fc) that mediates effector functions.
| Component | Description | Role |
|---|---|---|
| Heavy Chains | Determine antibody isotype (e.g., IgG, IgA) | Dictate effector functions (e.g., complement activation) |
| Light Chains | Contribute to antigen recognition | Can be either κ or λ type (no functional difference) |
| Variable (V) Regions | Hypervariable sequences at amino termini | Bind specific epitopes on antigens |
| Constant (C) Regions | Conserved sequences | Interact with immune cells (e.g., Fc receptors) |
IgG Antibody Characteristics
IgG is the most abundant antibody isotype in human serum, with a molecular weight of ~150 kDa . Its structure includes:
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Two Fab fragments: Each contains paired V regions (V_H and V_L) for antigen binding.
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One Fc fragment: Composed of the C-terminal domains of heavy chains, enabling interactions with Fc receptors and the complement system.
Key Properties
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Hinge region: Confers flexibility between Fab and Fc fragments.
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Cross-linking: Bivalent binding enhances antigen retention (e.g., agglutination of pathogens) .
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Subclasses: IgG1–4 differ in Fc-mediated functions (e.g., IgG1 strongly activates complement) .
COVID-19 Antibody Responses
Recent studies highlight antibody dynamics in SARS-CoV-2 infection:
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Early IgM and IgA responses: Detectable within days post-infection but wane over time .
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Persistent IgG responses: Correlate with long-term immunity and vaccine efficacy .
Therapeutic Applications
Engineered antibody fragments, such as single-chain Fv (scFv), are being explored for targeted therapies. These molecules combine V_H and V_L domains via synthetic linkers, enabling tissue penetration and toxin conjugation (e.g., immunotoxins for cancer) .
Product Specs
Constituents: 50% Glycerol, 0.01M Phosphate Buffered Saline (PBS), pH 7.4
