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Electrochemical Biosensors Based on Silver Solid Amalgam for Analysis in Flow Systems
Josypčuk, Oksana ; Barek, J. ; Josypčuk, Bohdan
In this contribution, the construction and preparation of 3 types of flow amperometric enzymatic biosensors based on silver solid amalgam (AgSA) were presented. Two of them consist of the tubular detector and enzymatic reactor of porous or powdered AgSA. The third biosensor was constructed using polished AgSA electrode. Reactors and polished AgSA electrodes were modified with thiols or chitosan and different enzymes were covalently immobilized by suitable techniques. Prepared biosensors were used for determination of ascorbic acid, glucose, hydrogen peroxide, catechol, pyrogallol, dopamine and sarcosine in model samples and in same cases in the real samples.
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Utilisation of enzymatic labelling with 4-aminophtalimide and 4-hydroxybenzylideneimidazolinone fluorescent derivates for monitoring of DNA-protein interaction
Orság, Petr ; Pivoňková, Hana ; Riedl, Jan ; Hocek, Michal ; Fojta, Miroslav
The 5’-substituted deoxycytosine triphosphates with conjugated solvatochromic derivates of 4-aminophtalimide (API) and derivates of the green fluorescent protein, 4-hydroxybenzylideneimidazolinone (HBI) were synthetized and successfully tested for enzymatic incorporation using primer extension assay. Site specifically labelled oligonucleotide probes were prepared and tested for interaction with p53 and SSB proteins, displaying distinct DNA-binding properties. The incorporation of multiple fluorescent labels did not interfere with natural protein binding and protein interaction leaded in both cases the to the gradual ratiometric increase of the fluorescence intensity moreover accompanied with the changes of the fluorescence emission spectra profile. Neither effect was observed after incubation with BSA, non-DNA binding protein, confirming the specificity of the interaction. Modified nucleoside triphosphates with conjugated fluorescence labels derivates of API and HBI can be used as substrates for preparation of the specific oligonucleotide labelled probes and provide the novel tool for studying and monitoring the DNA-protein interaction.
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Electrochemical analysis of DNA using switchable redox moieties
Fojta, Miroslav ; Daňhel, Aleš ; Horáková Brázdilová, Petra ; Plucnara, Medard ; Pivoňková, Hana ; Havran, Luděk ; Vidláková, Pavlína ; Raindlová, Veronika ; Balintová, Jana ; Macíčková-Cahová, Hana ; Hocek, Michal
Labelling of DNA with electrochemically active moieties proved to be a convenient way to the development of electrochemical techniques for the sequence-specific DNA sensing. Through combinations of various labels differing in redox potentials, independent redox coding of different DNA sequences or individual nucleobases can be attained. Applications possibilities of electrochemistry in analysis of modified DNAs are further extended by facile monitoring of chemical conversion of reactive groups on DNA during post-labelling with ultimate redox labels. In addition, controlled in situ electrochemical conversions of specific intrinsic and extrinsic DNA components can be utilized to switch their electrochemical signals and improve signal resolution.
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Polymerase synthesis of new photocaged DNA
Vaníková, Zuzana ; Hocek, Michal
5-[(2-nitrobenzyl)oxymethyl]-2’-deoxyuridine 5’-O-triphosphate (dUNBTP) and 5-hydroxymethyl-2’- deoxyuridine 5’-O-triphosphate (dUHMTP) were incorporated to diverse DNA sequences by polymerase synthesis (PEX or PCR). UHM modified DNA was synthesized also through the photolysis of photocaged, UNB-linked DNA. The presence of bulky NB-modification in the recognition sequence of DNA resulted in blocking of cleavage by all restriction endonucleases (REs), however sequences with small HM-modification (formed after irradiation by UV) were perfectly cleaved by all enzymes. Using of photoremovable protecting group in the DNA sequence presents bioorthogonal chemical masking and it has a potential in gene manipulation and cloning.
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Preparation of modified oligonucleotides by nicking enzyme amplification reaction
Ménová, Petra ; Hocek, Michal
A method for the enzymatic synthesis of short (10-22 nt) base-modified oligonucleotides was developed, based on the nicking enzyme amplification reaction. The methodology, including product isolation and purification, was scaled up to nanomolar amounts. The modified oligonucleotides were successfully used as primers in primer extension and PCR, affording primer-modified oligonucleotides and DNA. Two simple and efficient methods for fluorescent labelling of the PCR products were also developed.
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Vinyl-modified DNA and its cleavage by restriction endonucleases
Mačková, Michaela ; Hocek, Michal
Three types of vinyl modified nucleoside triphosphates (dNVTPs) were prepared by single step aqueous Suzuki- Miyaura cross-coupling reaction of halogenated 2’-deoxynucleotides with vinyltrifluoroborate. These dNVTPs were enzymatically incorporated into DNA in Primer extension experiments and Polymerase chain reaction. Primer extension products were then tested for cleavage by series of type II restriction enzymes and the results were compared with a cleavage of ethynyl-modified DNA.
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Polymerase synthesis of base-modified DNA: New methods and new applications
Balintová, Jana ; Daďová, Jitka ; Kielkowski, Pavel ; Ménová, Petra ; Vaníková, Zuzana ; Riedl, Jan ; Raindlová, Veronika ; Fojta, Miroslav ; Hocek, Michal
Diverse base-modified oligonucleotides and double-stranded DNA molecules were prepared by polymerase incorporation of modified nucleoside triphosphates. The methods include primer extension, PCR, nicking enzyme amplification reaction and mixed incorporations. The modified nucleic acids were used in redox and fluorescence labelling and coding, as well as regulation of binding and cross-linking with proteins.
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