Amino acid sequence and side chain specific synthetic receptors targeting protein phosphorylation

Sammanfattning: Antibodies have become a critical component of many diagnostic assays and are used for therapeutic purposes. Nevertheless they often fail to meet the strict performance demands raised in industry and in the clinic (e.g. stability, reproducibility, selectivity, affinity). These issues are especially notable for assays targeting post translational modifications (PTM) of proteins (phosphorylation, glycosylation, sulfation etc.). Antibody-based technologies suffer from problems of a more general nature associated with the analytical use of biological receptors i.e.: i) limited stability requiring cold chain logistics, ii) high production costs, iii) batch to batch variability. The above emphasizes the need for alternative robust, reproducible and low cost “binders” and assays. The aim in this thesis is to design, develop and test molecularly imprinted polymers (MIPs) which were synthesized epitope and stoichiometric imprinting approaches targeting phosphorylation as a PTM. Protein phosphorylationis one of the most common PTM, which is based on covalent attachment of phosphate group to particular amino acids. Misregulation of phosphorylation process is found related with diseases such as cancer, diabetes, and neurodegeneration. MIPs are synthesized through copolymerization of functional monomers and crosslinkers in the presence of N- and C- terminal protected templates. The key recognition element employed in developed synthetic receptors was 1,3-diaryl urea functionalmonomer 1. This monomer is a potent hydrogen bond donor forming strong cyclichydrogen bonds with oxyanions. Amino acid sequence specific and side chain imprinted binders were prepared targeting phosphorylation on tyrosine (pTyr) and on histidine (pHis). pHis MIP-based approach is proposed as a solution to enrich pHis peptides in the presence of other phosphoesters such as phosphoserine (pSer) in complex mixture without pre-treatment like β-elimination. In pTyr, ZAP-70 (zeta associated 70 kDa protein), which is prognosticator for chronic lymphocytic leukemia (CLL), and pTyr-sequence specific motif Src-SH2 domain were chosen as targets to evaluate regio- or stoichiometric selectivity performance of imprinted polymers. The synthesized polymers are used as effective enrichment tools for target phosphorylated peptides from complex mixture prior to mass spectrometry. Overall, the results demonstrate unique proteomics enrichment tools that link with personalized medicine relying on diagnostic coupled cancer treatment strategies based on kinase inhibitors.