Combinatorial Methodology. Screening for affinity specific ligands to biological and artificial receptors

University dissertation from Pure and Applied Biochemistry (LTH)

Abstract: Combinatorial screening methodology has been employed to select new affinity specific ligands to bilogical and artificial receptors. The screening methodology, in particular screening of combinatorial phage display peptide libraries against target molecules differing in function and shape, is focused upon. A linear combinatorial phage display hexapeptide library has been used to select novel peptides interacting with single stranded DNA, an oligonucleotide consisting of seven cytosines. The ability of a small peptide to act as specific recognition element to single stranded DNA is discussed. Linear hexapeptides interacting with surface structures not involved in the biologically active site on alpha-chymotrypsin were selected using phage display technology. The use of such peptides in analysis and separation applications is discussed. A novel cyclic peptide functioning as a specific inhibitor to the enzyme alpha-chymotrypsin has been selected from a random phage display nonapeptide library and characterized. The importance of conformation of the peptide on the inhibiting capacity is demonstrated. Peptides interacting with the invariable regions (Fc) of immunoglobulins have been selected from a phage display decapeptide library. The peptids have been shown to exhibit varying specificities to immunoglobulins from different subclasses and immunoglobulins originating from different species. The use of such peptides i analysis and separation applications is discussed. In addition, via the conceptof Molecular Imprinting Technology, a method which involves casting a polymeric network around a template molecule leaving a cavity or imprint when removed, the production of new polymeric artificial target molecules to be used in screening applications is demonstrated. Molecular imprinting technology has been used to prepare artificial polymeric steroid receptors for screening a combinatorial steroid library.

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