4HJU: Transthyretin In Complex With (e)-n-(3-(4-hydroxy-3,5-dimethylstyryl) Phenyl)acrylamide

Small molecules that react selectively with a specific non-enzyme drug-target protein in a complex biological environment without displacement of a leaving group (tracelessly) are rare and highly desirable. Herein we describe the development of a family of fluorogenic stilbene-based vinyl amides and vinyl sulfonamides that covalently modify transthyretin (TTR) tracelessly. These small molecules bind selectively to TTR in complex biological environments and then undergo a rapid and chemoselective 1,4-Michael addition with the pKa-perturbed Lys-15 epsilon-amino group of TTR. Replacing the vinyl amide in 2 with the more reactive vinyl sulfonamide in 4 hastens the conjugation kinetics. X-ray cocrystallography verified the formation of the secondary amine bond mediating the conjugation in the case of 2 and 4 and confirmed the expected orientation of the stilbene within the TTR binding sites. Vinyl amide 2 and vinyl sulfonamide 4 potently inhibit TTR dissociation and amyloid fibril formation in vitro. The TTR binding selectivity, modification yield, and reaction chemoselectivity of vinyl sulfonamide 4 are good enough in human plasma to serve as a starting point for medicinal chemistry efforts. Moreover, vinyl sulfonamide 4 is fluorogenic: it exhibits minimal background fluorescence in complex biological environments, remains dark upon binding to TTR, and becomes fluorescent only upon reaction with TTR. The fluorogenicity of 4 was utilized to accurately quantify the native TTR concentration in Escherichia coli lysate using a fluorescence plate reader.
PDB ID: 4HJUDownload
MMDB ID: 115638
PDB Deposition Date: 2012/10/14
Updated in MMDB: 2013/12
Experimental Method:
x-ray diffraction
Resolution: 1.35  Å
Source Organism:
Similar Structures:
Biological Unit for 4HJU: tetrameric; determined by author
Molecular Components in 4HJU
Label Count Molecule
Proteins (4 molecules)
Transthyretin(Gene symbol: TTR)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

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