Oligopeptides chains

Steps a and b of this synthetic procedure were performed under standard activation and oxidation conditions. It is advantageous that in the final deprotection step c the trimethylsilylethyl group is cleaved by / -fragmentation by the action of TBAF simultaneously with tert-hutyl protective groups present in the oligopeptide chain. 

Hitz, T. and Luisi, R L. (2004). Spontaneous onset of homochirality in oligopeptide chains generated in the polymerization of IV-carboxyanhydride amino acids in water. Orig. Life Evol. Biosph., 34 (1-2), 93-110. 

Figure 14.1. Construction of query saccharide structure for energy minimization with SWEET. Three-letter codes (IUBMB) for monosaccharides and amino acids are employed to construct oligosaccharide or oligopeptide chains. For monosaccharides, a- and p-anomers are prefixed with a and b, respectively. Pyranose and furanose rings are denoted as p and f, respectively.

Figure 6 Perspective drawing of terminally blocked L-alanine, the backbone of which may be considered a prototype of a section of an oligopeptide chain. The dashed lines indicate the limits of the alanine residue. The Greek letters designate the backbone dihedral angles.22 For larger side chains, the dihedral angles for rotation about the side-chain bonds are designated by x1. X2, and so on.22...

The average conformation of the oligopeptide chain is then taken as the combination of the average values of 4> and i / for all individual residues. 

Haas E, Katchalski-Katzir E, Steinberg I. Brownian motion of the ends of oligopeptide chains in solution as estimated by energy transfer between the chain ends. Biopolymers 1978 17 11-31. Haas E, Steinberg I. Intramolecular dynamics of chain molecules monitored by fluctuations in efficiency of excitation energy transfer. Biophys. J. 1984 46 429-437. 

Apart from hpid molecules, the molecules that are most commonly employed for the fabrication of biomimetic membranes are hydrophilic spacers and thi-olipids. Hydrophihc spacers consist of a hydrophihc chain (e.g., a polyethyleneoxy or oligopeptide chain) terminated at one end with an anchor group for tethering to a support and, at the other end, with a hydrophihc functional group (e.g., a... 

Fig. 12.14. Energy profiles along the Si and Sq cis — trans photoisomerization coordinate of the chromophore in blue included in the oligopeptide chain (adapted from Ref. [58]).

Fig. 12.15. Structure of frcini-NMTAA. Zrani-NMTAA can be inserted in an oligopeptide chain and photoisomerized to its cis form (adapted from Ref. [60]).

Figure 8.10 Cartoon representing a racemic template, composed of isotactic oligopeptide chains [shown as sequences ofleft- and right-hands], exerting a regioenantioselective incorporation of new monomers (shown as single isolated left- and right-hands) during the chain-elongation step of the polymerization.

Figure 8.23 Schematic representation of a racemic 8-sheet architecture composed of isotactic (R)- (black) and (S)- (red) oligopeptide chains, showing the enantioselective reaction with a (R)-thio-ester-monomer molecule only at the left-side rim. The monomer molecule is prevented from reacting at the right-side rim.

PPEs have recently been utilized in the dosimetric detection of proteases [197,198]. PPE 131 was substituted with an oligopeptide that carries a dinitroaniline quencher. The oligopeptide contains a motif that is susceptible toward protease action. This construct is nonfluorescent, because the dangling dinitroaniline imits quench the PPE s fluorescence. Upon exposure to low loadings of trypsine, a nonselective hydrolytic enzyme, the fluorescence of the quencher-less PPE 132 is observed. The oligopeptide chain was selected because it could be a substrate for matrix metalloproteases (human collagenase III) associated with human cancer cells. The peptide does not have to be covalently attached to the PPE Pinto and Schanze [198] were able to demonstrate that electrostatic interactions are likewise efficient in the detection of proteases by PPEs (Scheme 6.41). 

In 2010, Tanaka s group investigated whether a chiral cyclic a-amino acid included in an oligopeptide chain could catalyze the epoxidation of different enones with high enantiomeric excess. They demonstrated that the a-helical secondary structure of the peptide catalyst is directly related to the chosen a,a-disubstituted amino acid [134]. Thus, they found that 5 mol% of a-helical nonamer 92 with urea-H2O2 as oxidant can catalyze the reaction with ee > 95% (Scheme 12.18). 

Haas, E., Katehalski-Katzir, E., SteinbCTg, I.Z. Brownian motion of ends of oligopeptide chains in solutirm as estimated by taiergy transfer between chain ends. Biopolymers 17,11-31 (1978)... 

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