Sequence-dependent binding of dipeptides by an artificial receptor in water.
An artificial dipeptide receptor (1) was designed and observed to bind the deprotonated dipeptide Ac-D-Ala-D-Ala-OH in buffered water with K = 33,100 M(-1), whereas other dipeptides such as Ac-Gly-Gly-OH or Ac-D-Val-D-Val-OH were bound less efficiently, by factors of more than 10 (K < 3000 M(-1)). The efficient binding and the pronounced sequence selectivity are the result of a combination of strong electrostatic contacts and size-discriminating hydrophobic interactions. To provide such a combination, a guanidiniocarbonylpyrrole cation was attached to a novel cyclotribenzylene-substituted alanine derivative 5, to provide a hydrophobic bowl-shaped cavity just large enough to bind a methyl group but not any larger alkyl chains, thus causing the receptor to prefer alanine to valine. We describe the synthesis of 1 and the evaluation of its complexation properties in UV and fluorescence titration studies.
Schmuck
Carsten
C
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. schmuck@chemie.uni-wuerzburg.de
Rupprecht
Daniel
D
Wienand
Wolfgang
W
D001665:Binding Sites; D004151:Dipeptides / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*
D004151:Dipeptides; D014867:Water