6w5a | pdb_00006w5a

Crystal Structure of the Fab fragment of humanized 5c8 antibody containing the fluorescent non-canonical amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine at pH 9.7

spinqualitylabelsall models 6w5a, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6w5a is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.75Å Ligands: DV7, PCA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Genetically encoded fluorescent noncanonical amino acids (fNCAAs) could be used to develop novel fluorescent sensors of protein function. Previous efforts toward this goal have been limited by the lack of extensive physicochemical and structural characterizations of protein-based sensors containing fNCAAs. Here, we report the steady-state spectroscopic properties and first structural analyses of an fNCAA-containing Fab fragment of the 5c8 antibody, which binds human CD40L. A previously reported 5c8 variant in which the light chain residue Ile(L)98 is replaced with the fNCAA l-(7-hydroxycoumarin-4-yl)ethylglycine (7-HCAA) exhibits a 1.7-fold increase in fluorescence upon antigen binding. Determination and comparison of the apparent pKas of 7-HCAA in the unbound and bound forms indicate that the observed increase in fluorescence is not the result of perturbations in pKa. Crystal structures of the fNCAA-containing Fab in the apo and bound forms reveal interactions between the 7-HCAA side chain and surrounding residues that are disrupted upon antigen binding. This structural characterization not only provides insight into the manner in which protein environments can modulate the fluorescence properties of 7-HCAA but also could serve as a starting point for the rational design of new fluorescent protein-based reporters of protein function. Structural Insights into How Protein Environments Tune the Spectroscopic Properties of a Noncanonical Amino Acid Fluorophore.,Henderson JN, Simmons CR, Fahmi NE, Jeffs JW, Borges CR, Mills JH Biochemistry. 2020 Sep 22;59(37):3401-3410. doi: 10.1021/acs.biochem.0c00474., Epub 2020 Sep 3. PMID:32845612 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Antibody 3D structures

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