Guest peptide

In biological recognition phenomena, protein-protein interactions are of primary importance. In an attempt to mimic these processes, LaBrenz and Kelly [51] synthesized the peptidic host 64. In this receptor, the dibenzofuran template separates the two peptide units by roughly 10 A and allows for the complexation of a guest peptide (65), as depicted in Fig. 21. The complex first forms a three-stranded, antiparallel /J-sheet that is stabilized by hydrogen bonds, electrostatic interactions, and aromatic-aromatic interactions between the dibenzofuran and the benzamide moieties. This complex can further self associate to form more complex structures. This example shows that structurally defined peptide nanostructures can interfere with biological recognition processes and potentially have therapeutic applications. 

Fig. 21. Binding equilibrium between host peptide 64 and guest peptide 65 [51]...

Thermal Stability of Repeating Polytripeptides (Gly-X-Y)i0 and Host-Guest Peptides, (GPO)3-GXY-(GPO)4, Containing Hydroxyproline and Fluoroproline ... 

Triple-Helix, Based on Host-Guest Peptide Studies ... 

Studies on host-guest peptides have shown that incorporation of a proline residue into peptides which have a high tendency to fold into ordered secondary structures disrupts the onset of helical as well as P-sheet conformations and increases solubility and coupling rates.f Based on this observation, serine- and threonine-derived oxazolidine, and cysteine-derived thiazolidine derivatives (pseudoprolines) were proposed as valuable tools for combining protection of their side-chain functions with the simultaneous solubilization of the peptide chain. Due to the induction of kink conformations in the peptide backbone, originating from the preference of these pseudoproline residues to adopt the cis-imide bond configuration, insertion of such derivatives into peptides prevents self-association and P-structure formation. 

Host-guest peptides with guest residues having a pronounced preference for the... 

Correspondingly, host-guest peptides containing guest residues with a high P-sheet potoitial ( H ) are to form a p-structure. 

Ffe. 11. CD plectra of the host-guest peptides Boc-L-Ala5-G2-L-Ala3-NH-PEG-M in TFE, c = 1,1 mg peptide/ml... 

A bowl-shaped Pd Ls precursor 269 undergoes dimerization in the presence of a nine-residue peptide in NaNOs aqueous solution by Scheme 4.24 to give a 1 1 cage complex of the Pd Lg coordination capsule 504 with large hydrophobic cavity this capsule is in equilibrium with its cavitand analog [25]. According to the NMR data, the guest peptide molecule adopts a-helical conformation within the hydrophobic cavity of 504 [25]. 

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