Artificial peptides sequences

The design of artificial peptide sequences for the preparation of responsive surfaces takes advantage of the wealth of literature and information available on how the sequence of amino acids in a peptide chain affect the overall properties of the peptide (Boyle Woolfson, 2011 Bromley et al., 2008). The two general strategies employed so far are the exploitation of charge effects on the secondary conformation of the peptide and the ability of dipole moments of helical peptides to direct an electric current (Figure 3.5). 

Figure 11.6 The patE gene in the patellamide biosynthetic gene cluster encodes the peptide precursor (sequence in rectangle box) of patellamide C and ulithiacyclamide. Substitution of the precursor cassette for ulithiacyclamide with an artificial cassette (sequence in ellipse region) resulted in the biosynthesis of a new unnatural peptide, eptidemnamide...

The DNA binding ability of peptide nanostructures has also been reported by the artificial dimerization of peptide sequences corresponding to the contact region of the transcriptional activator protein GCN4. Cuenoud and Schepartz... 

Artificial peptides, such as GALA and JTS-1, and the sequence of the /V-terminal segment of VP1 of HRV2 rhinovirus, have also been found to enhance the transfection efficiency of polylysine conjugates/ DNA complexes (Table 16.1). These peptides, which contain acid residues (mainly glutamate) were shown to induce membrane fusion and permeabilization at pH lower than 6. Permeabilization and fusion activities... 

The peptide sequence was chosen to allow formation of an a-helix in water with the hydrophobic leucine residues pointing towards one side of the helix and the hydrophilic lysine residues towards the other. As expected, Oxaldies 1 and 2 catalyzed the decarboxylation of oxaloacetate. Both carboxyl groups are believed to interact with lysine residues, whereas acetoacetate, with only one carboxyl group, is not a substrate. The reaction shows Michaelis-Menten kinetics and accelerates decarboxylation 103-104-fold faster than n-butylamine as control, a record for a chemically derived artificial enzyme. In addition, the degree of reactivity seems to correlate with helix formation of the peptide. 

Recognition of a specific amino acid sequence from a protein or a specific tag peptide sequence is expected to lead to variety of medical and materials applications. Whereas the recognition of a single amino acid residue by synthetic hosts has been reported previously, the artificial recognition of a sequence of two or more amino acid residues has been quite limited. There are only a few reports on the... 

Some natural ion channels are believed to form amphiphilic a-helix bundles in hydrophobic lipid membranes, where the a-helices assemble with their hydrophilic parts facing each other, resulting in a hydrophilic channel. If artificial peptides that had appropriate combinations of both hydrophobic amino acid residues and hydrophobic amino acid sequences were used, the peptides would self-assemble to form a hydrophilic pathway in the lipid membrane. 

Quite recently we synthesized truly biomimetic receptors which contain, as spacers between crown ether and ammonium units, peptides instead of unnatural spacers as in 14 and IS. Host compounds such as 21 not only discriminate natural peptides by length and sequence, but are capable, in principle, of chiral recognition. They allow one to study in various media the energetics of side-chain interactions in P-sheet-like structures in a systematic way, exemplifying both the practical and the theoretically interesting aspects in the development of artificial peptide receptors. 

The surface plasmon resonance experiments with artificial peptides demonstrated that a peptide with the sequence... 

Adsorption of proteins from solution onto synthetic materials is a key factor in the response of a living body to artificial implanted materials and devices. Adsorbed proteins mediate cell attachment and spreading through specific peptide sequence-integrin receptor interactions and may therefore favorably influence the mechanical stability of the subsequently developed tissue—implant interface. However, the uncontrolled nonspecific adsorption of proteins from the extracellular matrix results in interfaces with many types of proteins in different conformations—a situation that is believed to cause deleterious reactions of the body, such as foreign-body response and fibrous encapsulation. ... 

Thiols have also been artificially introduced at the end of peptide sequences, with the advantage that the orientation of the peptide on the surface is not restricted by the geometry of cysteine. Furthermore, the use of disulfide linkers provides stronger adhesion forces per molecule, as they result in the formation of two gold-thiol links per molecule (Yasutomi et al., 2004 Yasutomi, Morita, Kimura, 2005). 

Responsive peptide surfaces may originate from biologically inspired peptide sequences or they may be artificially designed based on our knowledge of the interactions of amino acids within a peptide chain. Both classes will be discussed here. Naturally inspired responsive peptide surfaces are based either on a protein mimic (a long peptide sequence that mimics the properties of a responsive protein) or on... 

Elastin-like polypeptides (ELPs) have been extensively studied due to the fact that they combine similar stimulus response properties to other artificial polymers such as poly(iV-isopropylacrylamide) (pNIPAM) with the advantages of a biologically derived material, that is, it is biocompatible, modular in its composition, and can be obtained by biological processes. ELPs are polypeptides that contain a short, repetitive peptide sequence, most commonly (VPGXG) that is derived from tropoelastin, the precursor of elastin. In this sequence, X represents any amino acid sequence except proline. Polypeptides composed of the pentapeptide repeat unit VPGXG possess a reversible lower critical solution temperature (LCST). Below the LCST, the peptide is soluble... 

---