Poly compounds peptide synthesis with

The introduction of azobenzene units in the side chains of poly(L-lysine) been achieved by means of various procedures and different azo-reagents. In some experiments, samples of poly(Lysine HCl) or poly(Lysine acetate) were reacted with p-phenyl azobenzoic acid in the presence of pivaloyl (trimethylacetyl) chloride (mixed anhydrides method). Although anhydrous conditions must be maintained during the preparation of the anhydride itself, the condensation reaction with the amino compound can be performed in aqueous medium. This is necessary in this case, as poly(Lysine) is insoluble in pure DMF and other organic solvents commonly used in peptide synthesis. 

The solution phase synthesis of peptides often results in mixtures of labelled, unlabelled compounds along with other impurities and requires extensive purification. A route using a solid phase approach [polyethylene glycol-poly-styrene PEG-PS derivatised with a xanthen-2-oxovalerate (XAL) linker] was recently developed [193] (Scheme 44). 

Besides classical resin beads, other polymeric carriers were also used for the synthesis ofpeptide libraries in various formats. Poly aery late-grafted polypropylene pins were used for the synthesis of the first combinatorial chemical library [1,2], This type of support continues to be heavily used in multiple peptide [27] and non-peptide [28] library synthesis. Cellulose paper, originally used by Frank et al. as a solid-phase support for oligodeoxy-ribonucleotide synthesis [29], has also been used as the support for multiple SPOT synthesis of peptide libraries [30,31], Polystyrene-grafted polyethylene film (PS-PE) may also be used in combinatorial peptide library synthesis [32], The specific feature of the membrane type of carrier is its dividability. This feature has been used for the synthesis of libraries with a nonstatistical distribution of library members, where no compound is missing and none is represented more than once [33],... 

Triazoles are important as reagents. 1,2,4-Triazole is useful as a catalyst for transacylation reactions, e.g. for the synthesis of peptides from A -protected amino-4-nitrophenyl esters and amino acids without racemization. Nitron 5, a mesoionic 1,2,4-triazole, forms an almost insoluble nitrate and is used for the detection and gravimetric determination of nitrate ions. Nitron forms a covalent compound with poly(4-chloromethylstyrene) which removes nitrate from drinking water. 

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