FcIII peptide 

FcIII peptide is a 13-amino-acid peptide that competitively binds the hinge region of IgG Fc fragment with high affinity. FcIII peptide has an inhibition constant K_i of 25 nM when competing with Protein A for binding sites. FcIII peptide displays high selectivity toward human IgG subtypes yet weak binding affinity for murine IgG1. FcIII peptide anchors IgG Fc through hydrophobic interactions formed by tryptophan and valine residues, alongside multiple hydrogen bonds and salt bridges. FcIII peptide alters the local microenvironment of conjugated fluorescein after binding IgG Fc, which triggers enhanced fluorescent signals. FcIII peptide can be applied to researches related to monoclonal antibody production.^[1][2].

FcIII peptide conjugated with fluorescein (50 nM; 0-2.5 g/L human IgG) binds strongly to purified human IgG, increasing the dynamic range of fluorescence polarization by 260 mP, with a half-maximal response concentration of 0.001 g/L^[1].
FcIII peptide conjugated with fluorescein increases by up to 2.1-fold in 0.01-100 g/L hydroxypropyl-β-cyclodextrin systems, a result that confirms the fluorescence enhancement induced by IgG binding is driven by a hydrophobic microenvironment. Unlabeled SpA binds specifically to this peptide in a competitive manner, and 500 nM SpA reduces the fluorescence intensity of the FcIII peptide-human IgG complex to the background level of the free peptide^[1].
FcIII peptide conjugated with fluorescein modulates the linear quantitative range for fluorescence intensity detection of human IgG while maintaining a stable fluorescence polarization response^[1].
FcIII peptide conjugated with fluorescein (100 nM; 0-2.5 g/L IgG) detects human IgG and adalimumab biosimilars in serum-free CHO-S cell culture medium^[1].
FcIII peptide potently inhibits the binding between the Z domain of Protein A and human IgG Fc, with a K_i value of 25 nM at pH 7.2^[2].
FcIII peptide uses Val-10 and Trp-11 as key residues for binding to human IgG Fc^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

1529.74

C₆₉H₉₆N₁₈O₁₈S₂

874909-17-8

Asp-Cys-Ala-Trp-His-Leu-Gly-Glu-Leu-Val-Trp-Cys-Thr-NH2 (disulfide bridge:Cys2-Cys12)

DCAWHLGELVWCT-NH2 (disulfide bridge:Cys2-Cys12)

O=C(N[C@@H](CSSC[C@@H](C(N[C@@H]([C@H](O)C)C(N)=O)=O)NC1=O)C(N[C@@H](C)C(N[C@@H](CC2=CNC3=CC=CC=C23)C(N[C@@H](CC4=CNC=N4)C(N[C@@H](CC(C)C)C(NCC(N[C@@H](CCC(O)=O)C(N[C@@H](CC(C)C)C(N[C@@H](C(C)C)C(N[C@H]1CC5=CNC6=CC=CC=C56)=O)=O)=O)=O)=O)=O)=O)=O)=O)[C@H](CC(O)=O)N

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Please store the product under the recommended conditions in the Certificate of Analysis.

• [1]. Patil U, et al. Antibody mix-and-read assays based on fluorescence intensity probes. mAbs. 2021;13(1):1980178.

  [2]. DeLano WL, et al. Convergent solutions to binding at a protein-protein interface. Science (New York, N.Y.). 2000 Feb 18;287(5456):1279-83.