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Reactive modifications of RNA for bioconjugations with proteins and new enzymatic methods for the synthesis of base-modified RNA
Brunderová, Mária ; Hocek, Michal (advisor) ; Míšek, Jiří (referee) ; Vaňáčová, Štěpánka (referee)
This doctoral thesis focuses on the enzymatic synthesis of base-modified RNA probes with diverse functional groups, including reactive cross-linking, hydrophobic and fluorescent moieties, or affinity tags. The construction of nucleobase-modified oligonucleotides is accomplished either through conventional in vitro transcription with T7 RNA polymerase or by an innovative approach leveraging engineered mutant DNA polymerases and primer extension reaction (PEX). In the first section of the thesis, a novel ribonucleoside triphosphate building block with reactive chloroacetamide functionality was synthesised using an aqueous Pd-catalysed Sonogashira cross- coupling reaction, directly applied on iodinated nucleotide. The chloroacetamide modified triphosphate was then tested as a putative substrate for T7 RNA polymerase in in vitro transcription reaction, aiming to construct RNA probes with one or multiple reactive groups. The selectivity of chloroacetamide- modified RNA for thiol-, or cysteine-, and histidine-containing (bio)molecules was demonstrated by model bioconjugation reactions and cross-linking experiments with three RNA-binding proteins of diverse structures and functions. The efficient formation of RNA-protein covalent adducts was confirmed by western blot or gel, and mass spectrometry analyses...
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Synthesis and delivery of novel fluorescently-labelled nucleotides and their nucleic acids for bio-analytical applications
Güixens Gallardo, Pedro ; Hocek, Michal (advisor) ; Zimčík, Petr (referee) ; Klán, Petr (referee)
1 Abstract The goals of the thesis were to synthesise novel fluorescently labelled nucleotides and the corresponding nucleic acids for bio-analytical applications as well as their delivery into cells. The thesis also aimed at the development of an effective method to inhibit non-templated incorporation of nucleotides. The problematic non-templated enzymatic incorporation of nucleotides is addressed by using several commercially available 5'-modified-oligonucleotides. The oligonucleotides (ONs) that we tested bore ortho twisted intercalating nucleic acid (oTINA), a trityl group, or biotin at the 5'-end. The modified ONs were used as templates in the enzymatic primer extension (PEX) experiments in the presence of either modified nucleotides or only natural deoxynucleoside triphosphates (dNTPs). The oTINA templates underwent PEX reaction using natural dNTPs and different DNA polymerases of the A or B family. In parallel, two types of fluorescent nucleoside derivatives were independently designed and synthesised. Firstly, we envisaged new fluorescent nucleotide tags containing the hexamethylated BODIPY moiety as a bright fluorescent label. Conversely, we focused on the improvement of fluorescent nucleotide probes sensitive to the viscosity or polarity. The fluorescently labelled methylated BODIPY nucleotides...
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Investigation of the compounds influencing the melting temperature of oligonucleotide probes
Kostelanský, Filip ; Zimčík, Petr (advisor) ; Hocek, Michal (referee) ; Krátký, Martin (referee)
Charles University, Faculty of Pharmacy in Hradec Kralove Department: Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Author: Mgr. Filip Kostelanský Supervisor: prof. PharmDr. Petr Zimčík, Ph.D. Doctoral Thesis: Investigation of the compounds influencing the melting temperature of oligonucleotide probes Real-time PCR is widely used method in various research fields like biomedicine, microbiology, veterinary medicine, etc. Quantification of gene expression, allelic discrimination and alteration detection are new and interesting application possibilities. Mismatch discrimination is not optimal when longer probes are used. Melting temperature difference between fully complementary duplex and mismatched duplex is negligible in the case of longer probes. The short oligodeoxynucleotide (ODN) probes, on the other hand, are suitable for good discrimination of single nucleotide variants. However, these probes suffer from low melting temperatures. Adding minor groove binders (MGB), or other substances, which can strongly interact with DNA such as intercalating dyes or polyamines, can increase the melting temperature of short probes duplexes. In this work, several series of acridine-4-carboxamide intercalators were synthesized. MGB (Hoechst 33258) and polyamine (spermine) were modified and...
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Enzymatic synthesis and study of properties of base-modified DNA
Viktorinová, Klára ; Hocek, Michal (advisor) ; Vrábel, Milan (referee)
The influence and specific interactions of chemical modifications in the DNA major groove have been systematically investigated for a long time. This work focuses on the enzymatic preparation of DNA bearing phenyl substituents on bases in milligram scale. For this synthesis, four 2'-deoxyribonucleoside triphosphates bearing an electron-rich phenyl group at position 7 of 7-deazapurines and at position 5 of pyrimidines (dAPhTP, dGPhTP, dCPhTP, dUPhTP) were prepared in prof. Hocek's group. The DNA polymerase KOD(exo-), which was expressed for the purpose of this work, was used to carry out the enzymatic synthesis. All four phenyl-modified 2'-deoxyribonucleoside triphosphates were successfully incorporated into the oligonucleotide chain using the primer extension and the DNA was synthesized in a milligram scale. The individual products were purified by dialysis and HPLC and their denaturation temperature was further monitored on UV-Vis spectrophotometer and their structure by spectroscopic method CD. The main objective of this and further extensive studies is mainly to understand the various biological processes and bioorthogonal reactions of macromolecules. [IN CZECH] Key words DNA, modifications, oligonucleotides, polymerases, PEX, PCR, structural analysis, CD
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Synthesis of fluorinated nucleosides
Nguyen, Van Hai ; Hocek, Michal (advisor) ; Baszczyňski, Ondřej (referee)
The key intermediate 6-amino-7-iodo-7-deazapurine 3'-deoxy-3'-fluororibonucleoside was synthesized using multistep sequence of several reactions, which started from the commercially available D-xylose and 6-chloro-7-deazapurine. The synthetic strategy was based on fluorination of sugar and glycosylation with corresponding nucleobase afterwards. The fluorination of 5-protected-1,2-isopropylidine xylose with different protecting groups at position 5 always led to elimination. It was later discovered that isopropylidine forces the conformation, which is unfavorable for substitution. During the extensive optimization it was also found out that DAST appears to be an optimal fluorinating agent. Fluorination was performed on 2,3-unprotected xylose, which was subsequently used for glycosylation. After several unsuccessful attempts on "protection group free" glycosylation, Vorbrüggen glycosylation was successful and gave desired 3'-fluoro nucleoside in good yield. However, benzoyl group had to be introduced into position 2'. The protected nucleoside was then aminated and simultaneously deproctected with solution of aqueous NH3 and 1,4-dioxane. The obtained key intermediate was used for synthesis of a small series of desired 6-amino-7-hetaryl nucleoside using Pd-catalyzed Suzuki reaction under aqueous...
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Approaches to the enzymatic synthesis of hypermodified DNA polymers
Ondruš, Marek ; Hocek, Michal (advisor) ; Janeba, Zlatko (referee) ; Zimčík, Petr (referee)
The aim of this thesis was to synthesize new series of modified 2'-deoxynucleoside triphosphates (dNTPs) bearing hydrophobic modifications, use them in enzymatic synthesis of fully-modified DNA and study its bio-physical properties. In the first part of the thesis, a set of four 2'-deoxynucleosides bearing a linear or branched alkane, indole or phenyl group were synthesized by Sonogashira cross-coupling reactions using alkynes and iodinated nucleosides. Ethynyl linkers of corresponding nucleosides were reduced by catalytic hydrogenation to obtain another four nucleosides bearing the modifications through alkyl linker. All eight nucleosides were then transformed into 2'-deoxynucleoside triphosphates (dNTPs) by Yoshikawa phosphorylation and individually tested as substrates for polymerase synthesis by primer extension (PEX). Their combinations were systematically tested to generate DNA containing one or even four modified nucleotides. It was possible to replace all four canonical nucleotides with hydrophobically-modified counterparts and thus synthesize DNA with high density of modifications. Nevertheless, only nucleotides bearing modifications through rigid ethynyl linker were suitable for synthesis of longer hypermodified DNA. Nucleotides with more flexible alkyl linker destabilized duplex during...
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Modified nucleotides and DNA for electrochemical labelling and defined display of small molecules
Krömer, Matouš ; Hocek, Michal (advisor) ; Křen, Vladimír (referee) ; Vrábel, Milan (referee)
This thesis is focused on enzymatic construction of DNA probes for electrochemical labelling, bioconjugations and, in the final part, building on knowledge gathered in previous chapters, it describes a method useful for construction of highly functionalized base-modified DNA enabling defined multivalent display of glycosides. In first chapter, a chemical route to diol-bearing nucleotides was found. Sonogashira reaction facilitated access to alkyne-tethered diols and subsequent catalytic hydrogenation, described for the first time in the literature, provided protection-free method for obtaining nucleotide diols tethered via flexible sp3 hybridized linker. Cleavage of alkane-linked, but not alkyne-linked, nucleotide diols yielded aliphatic nucleotide aldehyde. All nucleotides were found to be good substrates for KOD XL DNA polymerase in both primer extension and polymerase chain reaction, apart from aldehyde-linked dUCHO TP nucleotide, which performed well in PEX reaction, but gave PCR products only in a mixture with natural dTTP. This could be overcome by cleavage of diol-modified DNA, which also yielded aldehyde-functionalized dsDNA. All reactive probes were examined for bioconjugations with fluorescent hydrazine, reductive amination with lysine or lysine-containing peptides or other molecules...
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Investigation of the compounds influencing the melting temperature of oligonucleotide probes
Kostelanský, Filip ; Zimčík, Petr (advisor) ; Hocek, Michal (referee) ; Krátký, Martin (referee)
Charles University, Faculty of Pharmacy in Hradec Kralove Department: Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Author: Mgr. Filip Kostelanský Supervisor: prof. PharmDr. Petr Zimčík, Ph.D. Doctoral Thesis: Investigation of the compounds influencing the melting temperature of oligonucleotide probes Real-time PCR is widely used method in various research fields like biomedicine, microbiology, veterinary medicine, etc. Quantification of gene expression, allelic discrimination and alteration detection are new and interesting application possibilities. Mismatch discrimination is not optimal when longer probes are used. Melting temperature difference between fully complementary duplex and mismatched duplex is negligible in the case of longer probes. The short oligodeoxynucleotide (ODN) probes, on the other hand, are suitable for good discrimination of single nucleotide variants. However, these probes suffer from low melting temperatures. Adding minor groove binders (MGB), or other substances, which can strongly interact with DNA such as intercalating dyes or polyamines, can increase the melting temperature of short probes duplexes. In this work, several series of acridine-4-carboxamide intercalators were synthesized. MGB (Hoechst 33258) and polyamine (spermine) were modified and...
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Modification of nucleic acids by reactive groups for bioconjugations and cross-linking with lysine-containing peptides and proteins
Ivancová, Ivana ; Hocek, Michal (advisor) ; Míšek, Jiří (referee) ; Urban, Milan (referee)
In the first part of this thesis, I developed reactive DNA probe for selective cross-linking with lysine residues of DNA-binding proteins. I synthesized 2'-deoxycytidine 5'-O-mono- and triphosphate bearing squaramate moiety tethered to the position 5 via propargylamine linker. The monophosphate was used as a model compound to test the reactivity of this mixed squaramate in cross-linking reactions with lysine and short lysine containing peptides. Squaramate modified 2'-deoxycytidine 5'-O-triphosphate was found to be suitable substrate for KOD XL polymerase in both PEX and PCR synthesis of modified DNA. Squaramate modified DNA forms stable diamide linkage with primary amines. I tested the reactivity of this DNA probe in bioconjugation reactions with sulfo-Cy5-amine and lysine containing peptides. Afterwards, squaramate-linked DNA was successfully cross-linked with lysine rich histone proteins. This reactive squaramate modified nucleotide showed potential for following bioconjugation reactions of nucleic acids with amines or lysine containing peptides and proteins without the need of external reagent. Based on positive results of experiments with squaramate modified DNA, in the second part of the thesis I developed and synthesized squaramate modified ribonucleotide to study cross- linking with RNA...
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