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Human IgG1 (SEHF: S267E/H268F)

Fc engineering vectors: CDC / Complement Modulated Family

Human IgG1 (SEHF: S267E/H268F)

$680.00

Plasmid Name: pHC-IgG1-SEHF(S267E/H268F)

Backbone: Human IgG1 heavy chain expression vector

Mutation Set: S267E / H268F

Complement Effect Level: ★★★★☆ (High-Potency CDC Enhancer)

High-potency CH2 double mutation designed to optimize the C1q binding loop. Substantially increases C1q binding affinity (>10-fold over wild-type) and CDC potency without requiring intermolecular hexamerization.

SKU: AFV-25 Category: Tags: , , , , , , ,

Plasmid Name
pHC-IgG1-SEHF(S267E/H268F)
Mutation Set
S267E / H268F
Selection Marker
Ampicillin
Promoter
CMV

Fc Engineering Overview

The Human IgG1 (SEHF: S267E/H268F) Fc variant introduces a high-potency double mutation in the CH2 domain designed to optimize the C1q binding loop. This substitution drives strong enhancement of C1q recruitment, C1q binding affinity (>10-fold over wild-type), and complement-dependent cytotoxicity (CDC) while simultaneously increasing FcγRIIb engagement and preserving normal FcRn-mediated recycling.

Functional Profile

Property Effect
FcγRIIb binding Strongly Increased ↑↑
FcγRIIIa binding / ADCC Moderate / Baseline to Slight Shift
CDC High-Potency Enhancement ↑↑↑ (>10 x C1q affinity)
FcRn binding Normal / WT Baseline
Serum half-life Normal / WT Baseline
Effector potency High-Potency CDC-Dominant (with enhanced FcγRIIb engagement)

Mechanism of Action

The SEHF Fc variant introduces two targeted substitutions—Ser267 to Glu and His268 to Phe—within the CH2 domain loop comprising residues 265–270. S267E introduces a strategic negative charge that enhances ionic interactions with C1q, while H268F provides favorable aromatic/hydrophobic packing. Together, this double mutation stabilizes the local backbone conformation to dramatically boost C1q binding affinity and accelerate membrane attack complex (MAC) assembly, providing a superior complement activation threshold compared to single-point or classical loop variants without requiring intermolecular hexamerization.

Phenotypic Effects

  • High-potency enhancement of complement-dependent cytotoxicity (CDC).
  • Substantially increased C1q binding affinity (>10-fold over wild-type IgG1).
  • Superior lytic activity against targets expressing low-to-moderate antigen density.
  • Simultaneous enhancement of inhibitory FcγRIIb binding.
  • Preserves normal FcRn-mediated recycling and systemic pharmacokinetics.

Applications

  • Therapeutic antibodies targeting low-density cell-surface antigens requiring potent CDC.
  • Oncology antibody formats engineered for robust complement-mediated cell lysis.
  • Dual-functional candidates requiring combined CDC enhancement and FcγRIIb cross-linking.
  • Alternative complement-boosting strategy for constructs incompatible with hexamerizing mutations.

Plasmid Map & Feature Annotation

Insert Structure: VH – CH1 – hinge – CH2(S267E/H268F) – CH3

  • VH: Variable heavy domain
  • CH1: Constant heavy 1
  • Hinge: Native IgG1 hinge
  • CH2(S267E/H268F): High-potency C1q-enhancing double mutation
  • CH3: Native IgG1 CH3

Product Note: The SEHF Fc variant represents a second-generation complement-enhancing module engineered via rational interface redesign. By directly optimizing the CH2 loop interface for C1q, SEHF provides higher CDC activity than classic modifications like WS (K326W/E333S) while maintaining standard monovalent Fc structure and monomeric expression performance.

Fusion BioLabs Complement Modulated Family Comparison Matrix

Variant Mechanism Complement Effect Primary Application & Notes
human IgG1 (WT)
Wild-Type		 Native C1q binding ★★☆☆☆ Baseline Control. Standard physiological C1q binding and CDC baseline for comparative assays.
human IgG1 (HexaBody-Extended)
E345K / E430G / E431K		 On-cell hexamerization ★★★★★+ Hyper-CDC Enhancer. Triple mutation maximizing Fc-Fc intermolecular interactions; yields ultra-potent C1q avidity against ultra-low density antigen targets.
human IgG1 (HexaBody)
E345K / E430G		 On-cell hexamerization ★★★★★ Canonical CDC-Boosting Fc. Enhances cell-surface hexamer assembly upon antigen binding to drastically boost C1q recruitment and membrane attack complex (MAC) formation.
human IgG1 (SEHF)
S267E / H268F		 C1q binding loop enhancement ★★★★☆ This Product. High-Potency CDC Enhancer. Optimizes local electrostatic and structural interactions with C1q to boost complement lysis without requiring hexamerization.
human IgG1 (WS)
K326W / E333S		 C1q binding loop enhancement ★★★☆☆ Strong CDC Enhancer. Synergistic double mutation in CH2 that significantly increases C1q binding affinity and complement killing.
human IgG1 (K322A)
K322A		 C1q contact site ablation ★☆☆☆☆ Selective Human IgG1 CDC-Null. Abolishes C1q binding and CDC while maintaining native FcγR engagement (ADCC+/ADCP+).
human IgG2 (K322A)
K322A		 C1q contact site ablation ★☆☆☆☆ Completely Silent Human IgG2 Control. Eliminates residual IgG2 C1q binding to yield a fully inert neutralizer (ADCCnull/ADCPnull/CDCnull).
mouse IgG2a (CompNull)
L235E + E318A / K320A / K322A		 Complement binding triad ablation ★☆☆☆☆ Murine CDC-Null Control. Completely abolishes complement activation in murine models while preserving mouse FcγR engagement for syngeneic in vivo studies.

Storage & Handling

  • Store plasmid at −20°C.
  • Avoid repeated freeze–thaw cycles.
  • Use sterile technique when handling.
  • Suitable for transient or stable mammalian expression.

References

  1. Moore GL, Chen H, Karki S, Lazar GA. Engineered Fc variant antibodies with enhanced ability to recruit complement and mediate effector functions. MAbs. 2010;2(2):181-189.
  2. Richards JO, Karki S, Lazar GA, Chen H, Dang W, Desjarlais JR. Optimization of antibody binding to FcgammaRIIa enhances macrophage phagocytosis of tumor cells. Mol Cancer Ther. 2008;7(8):2517-2527.

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