PAA oligomers

A series of peptide-PAA oligomers was prepared on solid support using two different synthetic strategies. The more flexible procedure, that can be fully automated and that is based on the assembling of simple commercially available building blocks, is illustrated in Scheme 7.6. 

Scheme 7.6. Scheme for the automated parallel synthesis of poly-N-acylated amines exemplified for one defined compound, e.g., PAA oligomer 12 exhibiting high binding affinity to MHC class 1 molecule H-2Kb [49]. 

More recently, Lee et al. [119, 120] described the synthesis of the same kind of particles (without, however, referring to the previous work of Kondo). The difference lies in the coverage of FesOa nanoparticles, which were in this case coated with either a bilayer of lauric acid or with PAA oligomers. For each surface treatment, the influence of the initiator (either potassium persulfate (KPS) [119] or AIBA [120]) on the mechanism of particle formation, PSD, and particle morphologies was discussed. PSD was generally quite broad and the iron oxide nanoparticles were either located in the PS core or adsorbed at the surface. Further encapsulation with poly(NIPAM-co-MAA) provided core-shell particles. 

Due to very limited solubility of PGA and PAA chains in toluene, it is advised to initiate the polymerization by living PCL oligomers, [fPr0-PCL-0]3Al, as prepared by eCL ROP promoted by Al(OfPr)3... 

The experimental data on fractionation by molecular weight are given in 52,53). Fig. 2 b shows changes in the MWD of PVPD (oligomer) after binding part of it in a polycomplex with PAA (polymer)S2) it is clear that the experimental pattern (Fig. 2b) corresponds to the theoretical one (Fig. 2a), i.e., the high-molecular fraction binds in a polycomplex while the low molecular one remains in the solution. 

G. Baeras et al.124 have studied the complex formation in the systems PAA-PEG, PMAA-PEG and PMAA-block copolymer of ethylene and propylene oxides by spectrometry when PMAA is added to the PAA complexes in the presence of a dye (bromocresol green). It is shown that PMAA is more susceptible to complex formation than PAA in the reaction with oligomers. 

The matrix does not possess initially any specific conformation, e.g. the PAA-PEG system in water and the PMAA-PEG system in a methanol-water (ft) 40 vol-%) mixture. In this case, irrespective of the ratio of the components (i.e. of /3), only one peak appears in the sedimentation diagram. This confirms the statistical distribution of oligomers between the matrix molecules. 

The method of polarized luminescence was used for studying the distribution of the PEG oligomer between molecules of the matrix128. The dependence of the relaxation time for labelled PMAA and PAA chains in the presence of PEG on the degree of filling of the matrix with the oligomer reveals the essential difference. This is related to a different distribution of PEG between the polyacid (PMAA and PAA) molecules (cf. also ref.125 ). 

Non-natural peptides involved in the stabilization of the MFIC class I molecules can be considered as the starting point for the discovery of new immune modulators such as antitumor vaccines and T-cell receptor agonists or antagonists [44-48]. In this context, poly-N-acylated amines (PAAs) as a new class of synthetic oligomers were developed and tested as ligands for the murine class I molecule H-2Kb [49]. Based on the natural cytotoxic T-cell epitope SIINFEKL, non-peptidic structural elements were introduced in the C-ter-minal part of the ligand including the anchor positions 5 (Phe) and 8 (Leu) (Fig. 7.7). 

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