8H7M image
Entry Detail
PDB ID:
8H7M
Keywords:
Title:
Structure of nanobody 11A in complex with parathion
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2022-10-20
Release Date:
2023-10-25
Method Details:
Experimental Method:
Resolution:
1.87 Å
R-Value Free:
0.21
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Nanobody 11A
Chain IDs:A, B
Chain Length:140
Number of Molecules:2
Biological Source:Camelus bactrianus
Ligand Molecules
Primary Citation
Structural Insights into the Stability and Recognition Mechanism of the Antiquinalphos Nanobody for the Detection of Quinalphos in Foods.
Anal.Chem. 95 11306 11315 (2023)
PMID: 37428097 DOI: 10.1021/acs.analchem.3c01370

Abstact

Nanobodies (Nbs) have great potential in immunoassays due to their exceptional physicochemical properties. With the immortal nature of Nbs and the ability to manipulate their structures using protein engineering, it will become increasingly valuable to understand what structural features of Nbs drive high stability, affinity, and selectivity. Here, we employed an anti-quinalphos Nb as a model to illustrate the structural basis of Nbs' distinctive physicochemical properties and the recognition mechanism. The results indicated that the Nb-11A-ligand complexes exhibit a "tunnel" binding mode formed by CDR1, CDR2, and FR3. The orientation and hydrophobicity of small ligands are the primary determinants of their diverse affinities to Nb-11A. In addition, the primary factors contributing to Nb-11A's limited stability at high temperatures and in organic solvents are the rearrangement of the hydrogen bonding network and the enlargement of the binding cavity. Importantly, Ala 97 and Ala 34 at the active cavity's bottom and Arg 29 and Leu 73 at its entrance play vital roles in hapten recognition, which were further confirmed by mutant Nb-F3. Thus, our findings contribute to a deeper understanding of the recognition and stability mechanisms of anti-hapten Nbs and shed new light on the rational design of novel haptens and directed evolution to produce high-performance antibodies.

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