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PDBsum entry 5hpm

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protein ligands Protein-protein interface(s) links
Immune system PDB id
5hpm

 

 

 

 

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Contents
Protein chains
213 a.a.
216 a.a.
12 a.a.
Ligands
NAG ×2
CY3 ×2
Waters ×279
PDB id:
5hpm
Name: Immune system
Title: Cetuximab fab in complex with cyclic linked meditope
Structure: Cetuximab fab light chain. Chain: a, c. Engineered: yes. Cetuximab fab heavy chain. Chain: b, d. Engineered: yes. N-acetyl-l-cysteine, cyclic amidated, acetylated linked meditope. Chain: e, f.
Source: Mus musculus, homo sapiens. Mouse, human. Organism_taxid: 10090, 9606. Expressed in: unidentified. Expression_system_taxid: 32644. Synthetic: yes. Synthetic construct. Organism_taxid: 32630
Resolution:
2.67Å     R-factor:   0.190     R-free:   0.232
Authors: K.P.Bzymek,J.C.Williams
Key ref: K.P.Bzymek et al. (2016). Cyclization strategies of meditopes: affinity and diffraction studies of meditope-Fab complexes. Acta Crystallogr F Struct Biol Commun, 72, 434-442. PubMed id: 27303895
Date:
20-Jan-16     Release date:   15-Jun-16    
PROCHECK
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 Headers
 References

Protein chains
No UniProt id for this chain
Struc: 213 a.a.
Protein chains
No UniProt id for this chain
Struc: 216 a.a.
Protein chains
No UniProt id for this chain
Struc: 11 a.a.
Key:    Secondary structure  CATH domain

 

 
Acta Crystallogr F Struct Biol Commun 72:434-442 (2016)
PubMed id: 27303895  
 
 
Cyclization strategies of meditopes: affinity and diffraction studies of meditope-Fab complexes.
K.P.Bzymek, Y.Ma, K.A.Avery, D.A.Horne, J.C.Williams.
 
  ABSTRACT  
 
Recently, a unique binding site for a cyclic 12-residue peptide was discovered within a cavity formed by the light and heavy chains of the cetuximab Fab domain. In order to better understand the interactions that drive this unique complex, a number of variants including the residues within the meditope peptide and the antibody, as well as the cyclization region of the meditope peptide, were created. Here, multiple crystal structures of meditope peptides incorporating different cyclization strategies bound to the central cavity of the cetuximab Fab domain are presented. The affinity of each cyclic derivative for the Fab was determined by surface plasmon resonance and correlated to structural differences. Overall, it was observed that the disulfide bond used to cyclize the peptide favorably packs against a hydrophobic `pocket' and that amidation and acetylation of the original disulfide meditope increased the overall affinity ∼2.3-fold. Conversely, replacing the terminal cysteines with serines and thus creating a linear peptide reduced the affinity over 50-fold, with much of this difference being reflected in a decrease in the on-rate. Other cyclization methods, including the formation of a lactam, reduced the affinity but not to the extent of the linear peptide. Collectively, the structural and kinetic data presented here indicate that small perturbations introduced by different cyclization strategies can significantly affect the affinity of the meditope-Fab complex.
 

 

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