Artificial ditopic Arg-Gly-Asp (RGD) receptors.

Carsten Schmuck, Daniel Rupprecht, Matthias Junkers, Thomas Schrader

Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. schmuck@chemie.uni-wuerzburg.de

Chemistry (Weinheim an der Bergstrasse, Germany) 2007

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Covalent fusion of two artificial recognition motifs for arginine and aspartate resulted in a new class of ditopic RGD receptor molecules, 1-4. The two binding sites for the oppositely charged amino acid residues are linked by either flexible linkers of different length (in 1-3) or a rigid aromatic spacer (in 4). These spacers are shown to be critical for the complexation efficiency of the artificial hosts. If the linkers are too flexible, as in 1-3, an undesired intramolecular self-association occurs within the host and competes with, and thereby weakens, substrate binding. The rigid aromatic linker in 4 prevents any intramolecular self-association and hence efficient RGD binding is observed, even in buffered water (association constant of K(a) approximately 3000 m(-1)). A further increase in hydrophobic contacts, as in host 16, can complement the specific Coulomb attractions, thereby leading to an even more stable complex (Ka=5000 m(-1)). The recognition events have been studied with NMR spectroscopy, UV/Vis spectroscopy, and fluorescence titrations.

Citation

Carsten Schmuck, Daniel Rupprecht, Matthias Junkers, Thomas Schrader. Artificial ditopic Arg-Gly-Asp (RGD) receptors. Chemistry (Weinheim an der Bergstrasse, Germany). 2007;13(24):6864-73