The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Ivo Frébort - One of the best experts on this subject based on the ideXlab platform.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative adenosine deaminase (EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties to well known mammalian adenosine deaminases, but exhibited much lower kcat values. Adenine was the most favored substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolyzed N6-substituted Adenines from the group of plant hormones cytokinins, cleaving them to inosine and the corresponding side-chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-disubstituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently found also for a reference sample of human adenosine deaminase (ADA1). ADA1, however, showed a different reaction mechanism than the yeast enzymes, hydrolyzing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF detectors. The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and as a consequence, it may compromise physiological or therapeutic effect of exogenously applied cytokinin Derivatives.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases.
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative ADA (adenosine deaminase; EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties with well-known mammalian ADAs, but exhibited much lower k(cat) values. Adenine was the most favoured substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolysed N6-substituted Adenines from cytokinins, a group of plant hormones, cleaving them to inosine and the corresponding side chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-di-substituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently shown for a reference sample of human ADA1. ADA1, however, showed a different reaction mechanism to that of the yeast enzymes, hydrolysing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF (quadrupole-time-of-flight) detectors.The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and, as a consequence, it may compromise the physiological or therapeutic effects of exogenously applied cytokinin Derivatives.
Hana Pospíšilová - One of the best experts on this subject based on the ideXlab platform.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative adenosine deaminase (EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties to well known mammalian adenosine deaminases, but exhibited much lower kcat values. Adenine was the most favored substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolyzed N6-substituted Adenines from the group of plant hormones cytokinins, cleaving them to inosine and the corresponding side-chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-disubstituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently found also for a reference sample of human adenosine deaminase (ADA1). ADA1, however, showed a different reaction mechanism than the yeast enzymes, hydrolyzing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF detectors. The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and as a consequence, it may compromise physiological or therapeutic effect of exogenously applied cytokinin Derivatives.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases.
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative ADA (adenosine deaminase; EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties with well-known mammalian ADAs, but exhibited much lower k(cat) values. Adenine was the most favoured substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolysed N6-substituted Adenines from cytokinins, a group of plant hormones, cleaving them to inosine and the corresponding side chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-di-substituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently shown for a reference sample of human ADA1. ADA1, however, showed a different reaction mechanism to that of the yeast enzymes, hydrolysing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF (quadrupole-time-of-flight) detectors.The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and, as a consequence, it may compromise the physiological or therapeutic effects of exogenously applied cytokinin Derivatives.
Wlodzimierz Kutner - One of the best experts on this subject based on the ideXlab platform.
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Molecularly imprinted polymer for recognition of 5-fluorouracil by RNA-type nucleobase pairing.
Analytical Chemistry, 2013Co-Authors: Tan-phat Huynh, Piotr Pieta, Francis D'souza, Wlodzimierz KutnerAbstract:A 6-aminopurine (Adenine) Derivative of bis(2,2′-bithienyl)methane, vis., 4-[2-(6-amino-9H-purin-9-yl)ethoxy]phenyl-4-[bis(2,2′-bithienyl)methane] or Ade-BTM, was designed and synthesized for recognition of 5-fluorouracil (FU), an antitumor chemotherapy agent, by RNA-type (nucleobase pairing)-driven molecular imprinting. The prepolymerization complex stoichiometry involved one FU molecule and two molecules of the Ade-BTM functional monomer. Molecular structure of this complex was thermodynamically optimized via density functional theory at the B3LYP/3-21G* level. The stability constant of the FU–Ade-BTM complex of 1:2 stoichiometry was K = 2.17(±0.07) × 107 M–2, as determined by titration with quenching of fluorescence of the bis(2,2′-bithienyl)methane moiety of Ade-BTM by the FU titrant, in benzonitrile, at 352 nm excitation. Next, (5-fluorouracil)-templated molecularly imprinted polymer (MIP-FU) films were deposited on indium–tin oxide (ITO) or Au film-coated glass slides, Pt disk electrodes, or 10-MHz ...
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Molecularly Imprinted Polymer for Recognition of 5‑Fluorouracil by RNA-type Nucleobase Pairing
2013Co-Authors: Tan-phat Huynh, Piotr Pieta, Francis D’souza, Wlodzimierz KutnerAbstract:A 6-aminopurine (Adenine) Derivative of bis(2,2′-bithienyl)methane, vis., 4-[2-(6-amino-9H-purin-9-yl)ethoxy]phenyl-4-[bis(2,2′-bithienyl)methane] or Ade-BTM, was designed and synthesized for recognition of 5-fluorouracil (FU), an antitumor chemotherapy agent, by RNA-type (nucleobase pairing)-driven molecular imprinting. The prepolymerization complex stoichiometry involved one FU molecule and two molecules of the Ade-BTM functional monomer. Molecular structure of this complex was thermodynamically optimized via density functional theory at the B3LYP/3-21G* level. The stability constant of the FU–Ade-BTM complex of 1:2 stoichiometry was K = 2.17(±0.07) × 107 M–2, as determined by titration with quenching of fluorescence of the bis(2,2′-bithienyl)methane moiety of Ade-BTM by the FU titrant, in benzonitrile, at 352 nm excitation. Next, (5-fluorouracil)-templated molecularly imprinted polymer (MIP-FU) films were deposited on indium–tin oxide (ITO) or Au film-coated glass slides, Pt disk electrodes, or 10-MHz quartz crystal resonators by potentiodynamic electropolymerization from solution of FU, Ade-BTM, and tris([2,2′-bithiophen]-5-yl)methane (TTM) cross-linking monomer at FU:Ade-BTM:TTM = 1:2:3 mol ratio. Then UV–visible and Fourier transform infrared (FT-IR) spectra of the MIP-FU films were recorded to confirm the FU template presence in the MIP-FU film and its subsequent release by extraction with methanol from this film. For determination of the stability constant of the complex of the MIP cavity and FU, piezoelectric microgravimetry (PM) under both batch- and flow-injection analysis conditions was used. For sensing application, three different transduction platforms [differential pulse voltammetry (DPV), capacitive impedimetry (CI), and PM] were integrated with the MIP-FU recognition unit. The limit of detection (LOD) was 56 nM, 75 nM, and 0.26 mM, for these chemosensors, respectively, indicating suitability of the former two for FU determination in blood plasma or serum (∼500 nM). Moreover, the CI chemosensor was appreciably more sensitive to FU than to their common interferences
Marek Sebela - One of the best experts on this subject based on the ideXlab platform.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative adenosine deaminase (EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties to well known mammalian adenosine deaminases, but exhibited much lower kcat values. Adenine was the most favored substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolyzed N6-substituted Adenines from the group of plant hormones cytokinins, cleaving them to inosine and the corresponding side-chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-disubstituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently found also for a reference sample of human adenosine deaminase (ADA1). ADA1, however, showed a different reaction mechanism than the yeast enzymes, hydrolyzing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF detectors. The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and as a consequence, it may compromise physiological or therapeutic effect of exogenously applied cytokinin Derivatives.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases.
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative ADA (adenosine deaminase; EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties with well-known mammalian ADAs, but exhibited much lower k(cat) values. Adenine was the most favoured substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolysed N6-substituted Adenines from cytokinins, a group of plant hormones, cleaving them to inosine and the corresponding side chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-di-substituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently shown for a reference sample of human ADA1. ADA1, however, showed a different reaction mechanism to that of the yeast enzymes, hydrolysing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF (quadrupole-time-of-flight) detectors.The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and, as a consequence, it may compromise the physiological or therapeutic effects of exogenously applied cytokinin Derivatives.
Ondřej Novak - One of the best experts on this subject based on the ideXlab platform.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative adenosine deaminase (EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties to well known mammalian adenosine deaminases, but exhibited much lower kcat values. Adenine was the most favored substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolyzed N6-substituted Adenines from the group of plant hormones cytokinins, cleaving them to inosine and the corresponding side-chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-disubstituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently found also for a reference sample of human adenosine deaminase (ADA1). ADA1, however, showed a different reaction mechanism than the yeast enzymes, hydrolyzing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF detectors. The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and as a consequence, it may compromise physiological or therapeutic effect of exogenously applied cytokinin Derivatives.
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Hydrolytic cleavage of N6-substituted Adenine Derivatives by eukaryotic Adenine and adenosine deaminases.
Bioscience Reports, 2008Co-Authors: Hana Pospíšilová, Marek Sebela, Ondřej Novak, Ivo FrébortAbstract:Homogeneous Adenine deaminases (EC 3.5.4.2) from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and a putative ADA (adenosine deaminase; EC 3.5.4.4) from Arabidopsis thaliana were obtained for the first time as purified recombinant proteins by molecular cloning of the corresponding genes and their overexpression in Escherichia coli. The enzymes showed comparable molecular properties with well-known mammalian ADAs, but exhibited much lower k(cat) values. Adenine was the most favoured substrate for the yeast enzymes, whereas the plant enzyme showed only very low activities with either Adenine, adenosine, AMP or ATP. Interestingly, the yeast enzymes also hydrolysed N6-substituted Adenines from cytokinins, a group of plant hormones, cleaving them to inosine and the corresponding side chain amine. The hydrolytic cleavage of synthetic cytokinin 2,6-di-substituted analogues that are used in cancer therapy, such as olomoucine, roscovitine and bohemine, was subsequently shown for a reference sample of human ADA1. ADA1, however, showed a different reaction mechanism to that of the yeast enzymes, hydrolysing the compounds to an Adenine Derivative and a side chain alcohol. The reaction products were identified using reference compounds on HPLC coupled to UV and Q-TOF (quadrupole-time-of-flight) detectors.The ADA1 activity may constitute the debenzylation metabolic route already described for bohemine and, as a consequence, it may compromise the physiological or therapeutic effects of exogenously applied cytokinin Derivatives.
