Peptide blocks, assembly

Scheme 1 The Concept of Template-Assembled Synthetic Proteins (TASP) Topological Templates Induce Folding of Covalently Attached Peptide Blocks into Predetermined Packing Arrangements 5 13 141...

As a result of the branched chain architecture, TASP molecules exhibit some unique conformational properties)5 12-14 47 75 76 148 For example, the folding to a compact state proceeds via two distinct steps the onset of secondary structure in the attached peptide blocks followed by their template-directed self-assembly to a three-dimensional packing topology. Due to its characteristic branched chain connectivity, the conformational space accessible in the unfolded state is considerably reduced compared to a linear chain of similar size (excluded volume effect), resulting in a smaller chain entropy. Thus, folded TASP molecules are expected to show higher thermodynamic stability compared to unbranched polypeptides of comparable size. 

Fig. 6.6.4. Reversible self-assembly of PEO-b-peptide block copolymers based on protein-folding motifs.

Assembly of peptide blocks typically starts with 0.05 mol of template resin. The base-labile N -fmoc-protecting groups were removed by incubation with 20% piperidine (v/v) in dimethylformamide for 20 min (Figure 2D). The four peptide blocks were assembled simultaneously (Figure 2E-G)... 

In Fmoc chemistry, Lys and Om are conveniently blocked with the Boc protecting group [155]. For more temporary protection, the l-(4,4 -dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) protecting group is useful in the preparation of branched peptides, multiple antigenic peptides (MAPs), cyclic peptides, template-assembled synthetic proteins (TASPs), and templates for combinatorial chemistry [156-161]. Dde is quasi-orthogonal because the use of dilute hydrazine to cleave Dde partially removes the A -... 

Cha JN, Bartl MH, Wong MS et al (2003) Microcavity lasing from block peptide hierarchically assembled quantum dot spherical resonators. Nano Lett 3(7) 907-911... 

The transition from hybrid block copolymers with a homopeptide block toward those with sequence-defined peptide segments enriches the self-assembly behavior strongly. Ayers et smdied water-soluble block copolymers composed of a PEO block and a peptide block with comb architecture, which was obtained by the controlled polymerization of oligopeptide... 

For each peptide to be cleaved, place a 4 ml glass collection vial scribed with the peptide code number in the collection rack in the lower chamber and carefully fit the block assembly together ensuring that the drain tubes enter all the vials. It is essential to scribe the tubes with a diamond pen as any writing with felt-tipped pen will be erased by the acid. 

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