2ZNX: 5-fluorotryptophan Incorporated Scfv10 Complexed To Hen Egg Lysozyme

Citation:
Abstract
To more fully understand the molecular mechanisms responsible for variations in binding affinity with antibody maturation, we explored the use of site specific fluorine labeling and (19)F nuclear magnetic resonance (NMR). Several single-chain (scFv) antibodies, derived from an affinity-matured series of anti-hen egg white lysozyme (HEL) mouse IgG1, were constructed with either complete or individual replacement of tryptophan residues with 5-fluorotryptophan ((5F)W). An array of biophysical techniques was used to gain insight into the impact of fluorine substitution on the overall protein structure and antigen binding. SPR measurements indicated that (5F)W incorporation lowered binding affinity for the HEL antigen. The degree of analogue impact was residue-dependent, and the greatest decrease in affinity was observed when (5F)W was substituted for residues near the binding interface. In contrast, corresponding crystal structures in complex with HEL were essentially indistinguishable from the unsubstituted antibody. (19)F NMR analysis showed severe overlap of signals in the free fluorinated protein that was resolved upon binding to antigen, suggesting very distinct chemical environments for each (5F)W in the complex. Preliminary relaxation analysis suggested the presence of chemical exchange in the antibody-antigen complex that could not be observed by X-ray crystallography. These data demonstrate that fluorine NMR can be an extremely useful tool for discerning structural changes in scFv antibody-antigen complexes with altered function that may not be discernible by other biophysical techniques.
PDB ID: 2ZNXDownload
MMDB ID: 69269
PDB Deposition Date: 2008/5/2
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Gallus gallus
Similar Structures:
Biological Unit for 2ZNX: dimeric; determined by author
Molecular Components in 2ZNX
Label Count Molecule
Proteins (2 molecules)
1
Scfv
Molecule annotation
1
Lysozyme C(Gene symbol: LYZ)
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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