Peptides, imprinting

Furthermore, the peptide-imprinted polymer bound its target selectively over other tri-peptides, in addition, the polymer also showed selectivity for the TV-terminal dipeptide subunit over other similar dipeptides (Table 1). 

Scheme 22 Schematic representation of the peptide imprinting process using Ni-NTA technology. Copolymerization of the (His-Ala)-Ni-NTA complex (46) with mono- and bisacrylamides followed by extraction of the peptide at pH 3 provides a polymer (P-38) containing Ni-NTA complexes capable of rebinding the template peptide.

Alternative approaches to imprint peptides via strong monomer template association have recently been reported, although no results of the chromatographic application of these phases have been shown. Strong complexation inducing a (3-sheet conformation was possible using a designed functional monomer (21) [71]. Peptides... 

Ins 1 jlns2 (19/7) Paternal (yolk sac) Peptide hormone Fetal GR phenotypic Duvillie et al 1997 effect of imprinting undefined... 

Rather than using the protein molecule as a whole, the imprinting of selected protein epitopes may present a more practical approach. Imprints of such patches may then act as receptors for these parts of the protein. It could be shown that an MIP imprinted with a tetrapeptide was able to recognize not only the template but also a protein bearing the same 3-amino acid terminus as the peptide template [129]. If this approach proves to be successful in other cases as well, MI-based recognition will no longer be limited to small molecules. The result will be even more antibody like biomimetic polymers. 

Stationary phases with specific molecular recognition properties for D,L-enantiomers of peptides have been tailored using the molecular imprinting technique. A template molecule is added to suitable monomer(s), the system is polymerized, and the chiral template molecule is washed out [128]. 

Hart BR, Shea KJ. Synthetic peptide receptors molecularly imprinted polymers for the recognition of peptides using peptide-metal interactions. J Am Chem Soc 2001 123 2072-2073. 

Hart BR, Shea KJ. Molecular imprinting for the recognition of N-terminal histidine peptides in aqueous solution. Macromolecules 2002 35 6192-6201. 

Kempe M, Mosbach K. Chiral recognition of N alpha-protected amino acids and derivatives in non-covalently molecularly imprinted polymers. Int J Peptide Protein Res 1994 44 603 -606. 

Shea and colleagues [109-111] added an exciting contribution to this field They created molecular imprints for the peptide melittin, the main component of bee venom, in polymer nanoparticles, resulting in artificial antibody mimics that can be used for the in vivo capture and neutralization of melittin. Melittin is a peptide comprising 26 amino acids which is toxic because of its cytolytic activity. Shea and colleagues strategy was to synthesize cross-linked, acrylamide-based MIP nanoparticles by a process based on precipitation polymerization using a small amount of surfactant. To maximize the specificity and the affinity for melittin, a number of hydrophilic monomers were screened for complementarity with the template. The imprinted nanoparticles were able to bind selectively the peptide with an apparent dissociation constant of Ax>app > 1 nM [109]. 

It is difficult to make water-soluble peptides form complexes with titanium alkoxide, because they are not soluble in organic solvents. Therefore, such templates cannot be imprinted by the complexation approach. Instead, they could be imprinted in Ti02-gel films by the alternate adsorption approach with Ti(0 Bu)4. Figure 6.24a shows a plot of alternate layer-by-layer assembly of 100 mM titanium butoxide (3 min adsorption in toluene/ethanol) and 10 mM glycyl-L-tyrosine (Gly-L-Tyr, 10 min adsorption in water). The template molecule was removed by treatment with 10 mM aqueous sodium hydroxide, as... 

The preceding results indicated that subtle geometrical structures of amino acids and peptides were imprinted in Ti02-gel matrices. It is conceivable that the imprinting effect is not restricted to geometrical differentiations. 

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