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Preparation of a library of methionine sulfoxide reductase for applications in synthesis of chiral sulfoxides
Havelka, Václav ; Míšek, Jiří (advisor) ; Hlouchová, Klára (referee)
Chiral sulfoxides are important compounds in the pharmaceutical and chemical industries, however, their enantioselective synthesis providing only one desired enantiomer is not fully mastered. Some natural enzymes can be used for the biocatalytic preparation of chiral sulfoxides. One of such enzymes is methionine sulphoxide reductase. Methionine sulphoxide reductase is an enzyme limiting the effects of reactive oxygen radicals in the organism resulting from oxygen metabolism. Its function is the reduction of methionine sulfoxide in proteins to methionine. There are two types of methionine sulphoxide reductase, methionine sulphoxide reductase A reducing only (S)-methionine sulphoxide and methionine sulphoxide reductase B reducing (R)-methionine sulphoxide. Methionesulfoxide reductase B is suitable for the preparation of (S)-sulfoxides, however its catalytic activity is not sufficient for practical use. Using the recombinant DNA and mutagenic PCR techniques, a methionine sulphoxide reductase B mutant library was prepared, and the extent and nature of mutation introduced was determined. This library will serve as a starting point for the controlled evolution of the enzyme to obtain clones with increased activity and reduced substrate specificity.
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Study of DNA-compatible Reactions and Their Utilisation for DNA Encoded Libraries
Havelka, Václav ; Míšek, Jiří (advisor) ; Kožíšek, Milan (referee)
DNA-encoded peptide libraries are the basis for in vitro selection methods that use various biological systems (phage display; yeast display; mRNA display). Despite the great success of these selection methods, their obvious disadvantage is the limited number of building blocks, which consist of only twenty proteinogenic amino acids. The involvement of other non- proteinogenic amino acids and other building blocks could significantly expand the range of possible applications of these selection methods. For example, the introduction of chemical modifications in amino acid side chains in such libraries would allow the effective study of post-translational modifications (phosphorylation, acylation, glycosylation, methylation, etc.) in living organisms. The aim of this work was to develop a method for preparation of a fully synthetic DNA encoded library of peptides. The basic steps for the preparation were the chemical synthesis of the peptide and associated enzymatic synthesis of encoding DNA. Compatibility of chemical reactions with DNA is essential for the synthesis of DNA-encoded peptide libraries. Because the final acidic deprotection of the side chains in the peptide is not compatible with DNA, two approaches have been tested to overcome this problem. The first was an attempt to develop finer...
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Preparation of a library of methionine sulfoxide reductase for applications in synthesis of chiral sulfoxides
Havelka, Václav ; Míšek, Jiří (advisor) ; Hlouchová, Klára (referee)
Chiral sulfoxides are important compounds in the pharmaceutical and chemical industries, however, their enantioselective synthesis providing only one desired enantiomer is not fully mastered. Some natural enzymes can be used for the biocatalytic preparation of chiral sulfoxides. One of such enzymes is methionine sulphoxide reductase. Methionine sulphoxide reductase is an enzyme limiting the effects of reactive oxygen radicals in the organism resulting from oxygen metabolism. Its function is the reduction of methionine sulfoxide in proteins to methionine. There are two types of methionine sulphoxide reductase, methionine sulphoxide reductase A reducing only (S)-methionine sulphoxide and methionine sulphoxide reductase B reducing (R)-methionine sulphoxide. Methionesulfoxide reductase B is suitable for the preparation of (S)-sulfoxides, however its catalytic activity is not sufficient for practical use. Using the recombinant DNA and mutagenic PCR techniques, a methionine sulphoxide reductase B mutant library was prepared, and the extent and nature of mutation introduced was determined. This library will serve as a starting point for the controlled evolution of the enzyme to obtain clones with increased activity and reduced substrate specificity.
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