Stilbene vinyl sulfonamides as fluorogenic sensors of and traceless covalent kinetic stabilizers of transthyretin that prevent amyloidogenesis

J Am Chem Soc. 2013 Nov 27;135(47):17869-80. doi: 10.1021/ja408230k. Epub 2013 Nov 18.

Abstract

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 ε-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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amides / chemistry
  • Amides / pharmacology
  • Amyloid / antagonists & inhibitors*
  • Amyloid / metabolism
  • Crystallography, X-Ray
  • Fluorescent Dyes / chemistry
  • Fluorescent Dyes / pharmacology*
  • Humans
  • Kinetics
  • Models, Molecular
  • Prealbumin / metabolism*
  • Stilbenes / chemistry
  • Stilbenes / pharmacology*
  • Sulfonamides / chemistry
  • Sulfonamides / pharmacology*

Substances

  • Amides
  • Amyloid
  • Fluorescent Dyes
  • Prealbumin
  • Stilbenes
  • Sulfonamides
  • vinyl sulfonamide