132696-16-3Relevant academic research and scientific papers
Interaction of the recombinant Herpes Simplex Virus type 1 thymidine kinase with thymidine and aciclovir: A kinetic study
Kussmann-Gerber, Susanna,Wurth, Christine,Scapozza, Leonardo,Pilger, Beatrice D.,Pliska, Vladimir,Folkers, Gerd
, p. 311 - 330 (1999)
Herpes Simplex Virus type 1 thymidine kinase (HSV 1 TK) is a key target for antiviral therapy and it phosphorylates a broad spectrum of nucleosides and nucleotides. We report the results from kinetic and inhibition experiments with HSV 1 TK, and show that there is a preferred, but not exclusive, binding order of substrates, i.e. dT binds prior to ATP. Furthermore, the results provide new informations on the mechanism of binding suggesting that HSV1 TK undergoes conformational changes during the catalytic cycle.
Prodrug activation by Cryptosporidium thymidine kinase
Sun, Xin E.,Sharling, Lisa,Muthalagi, Mani,Mudeppa, Devaraja G.,Pankiewicz, Krzysztof W.,Felczak, Krzysztof,Rathod, Pradipsinh K.,Mead, Jan,Striepen, Boris,Hedstrom, Lizbeth
, p. 15916 - 15922 (2010)
Cryptosporidium spp. cause acute gastrointestinal disease that can be fatal for immunocompromised individuals. These protozoan parasites are resistant to conventional antiparasitic chemotherapies and the currently available drugs to treat these infections are largely ineffective. Genomic studies suggest that, unlike other protozoan parasites, Cryptosporidium is incapable of de novo pyrimidine biosynthesis. Curiously, these parasites possess redundant pathways to produce dTMP, one involving thymidine kinase (TK) and the second via thymidylate synthase-dihydrofolate reductase. Here we report the expression and characterization of TK from C. parvum. Unlike other TKs, CpTK is a stable trimer in the presence and absence of substrates and the activator dCTP. Whereas the values of kcat= 0.28 s-1 and Km,ATP = 140 μM are similar to those of human TK1, the value of Km(thymidine) = 48 μM is 100-fold greater, reflecting the abundance of thymidine in the gastrointestinal tract. Surprisingly, the antiparasitic nucleosides AraT, AraC, and IDC are not substrates for CpTK, indicating that Cryptosporidium possesses another deoxynucleoside kinase. Trifluoromethyl thymidine and 5-fluorodeoxyuridine are good substrates for CpTK, and both compounds inhibit parasite growth in an in vitro model of C. parvum infection. Trifluorothymidine is also effective in a mouse model of acute disease. These observations suggest that CpTK-activated pro-drugs may be an effective strategy for treating cryptosporidiosis.
Synthesis and application of isotopically labeled flavin nucleotides
Mishanina, Tatiana V.,Kohen, Amnon
, p. 370 - 375 (2015)
Flavin nucleotides, i.e. flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), are utilized as prosthetic groups and/or substrates by a myriad of proteins, ranging from metabolic enzymes to light receptors. Isotopically labeled flavins have served as invaluable tools in probing the structure and function of these flavoproteins. Here we present an enzymatic synthesis of several radio- and stable-isotope labeled flavin nucleotides from commercially available labeled riboflavin and ATP. The synthetic procedure employs a bifunctional enzyme, Corynebacterium ammoniagenes FAD synthetase, that sequentially converts riboflavin to FMN and then to FAD. The final flavin product (FMN or FAD) is controlled by the concentration of ATP in the reaction. Utility of the synthesized labeled FAD cofactors is demonstrated in flavin-dependent thymidylate synthase. The described synthetic approach can be easily applied to the production of flavin nucleotide analogues from riboflavin precursors. Flavin nucleotides are utilized as prosthetic groups and/or substrates by a myriad of proteins. Here we present an enzymatic synthesis of several radio- and stable-isotope labeled flavin nucleotides. Utility of the synthesized labeled FAD cofactors is demonstrated in flavin-dependent thymidylate synthase. The described synthetic approach can be easily applied to the production of flavin nucleotide analogues from riboflavin precursors.
Mutation of Gln125 to Asn selectively abolishes the thymidylate kinase activity of herpes simplex virus type 1 thymidine kinase
Degreve, Bart,Esnouf, Robert,De Clercq, Erik,Balzarini, Jan
, p. 285 - 293 (2001)
The broad substrate specificity of herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) has provided the basis for selective antiherpetic therapy and, more recently, suicide gene therapy for the treatment of cancer. We have now constructed an HSV-1 TK mutant enzyme, in which an asparagine (N) residue is substituted for glutamine (Q) at position 125, and have evaluated the effect of this amino acid change on enzymatic activity. In marked contrast with wild-type HSV-1 TK, which displays both thymidine kinase and thymidylate kinase activities, the HSV-1 TK(Q125N) mutant was unable to phosphorylate pyrimidine nucleoside monophosphates but retained significant phosphorylation activity for thymidine and a series of antiherpetic pyrimidine and purine nucleoside analogs. The abrogation of HSV-1 TK-associated thymidylate kinase activity resulted in a 100-fold accumulation of the monophosphate form of (E)-5(2-bromovinyl)-2′-deoxyuridine (BVDU) in osteosarcoma cells transfected with the HSV-1 TK(Q125N) gene compared with osteosarcoma cells expressing wild-type HSV-1 TK. BVDU monophosphate accumulation gave rise to a much greater inhibition of cellular thymidylate synthase in HSV-1 TK(Q125N) gene-transfected cells than wild-type HSV-1 TK gene-transfected osteosarcoma tumor cells without significantly changing the cytostatic potency of BVDU for the HSV-1 TK gene-transfected tumor cells. Accordingly, the presence of the Q125N mutation in HSV-1 TK gene-transfected tumor cells was found to result in a multilog decrease in the cytostatic activity of those pyrimidine nucleoside analogs that in their monophosphate form do not have marked affinity for thymidylate synthase [i.e., 1-β-D-arabinofuranosylthymine and (E)-5-(2-bromovinyl)-1-β-D-arabinofuranosyluracil].
Trapping of an intermediate in the reaction catalyzed by flavin-dependent thymidylate synthase
Mishanina, Tatiana V.,Koehn, Eric M.,Conrad, John A.,Palfey, Bruce A.,Lesley, Scott A.,Kohen, Amnon
, p. 4442 - 4448 (2012)
Thymidylate is a DNA nucleotide that is essential to all organisms and is synthesized by the enzyme thymidylate synthase (TSase). Several human pathogens rely on an alternative flavin-dependent thymidylate synthase (FDTS), which differs from the human TSase both in structure and molecular mechanism. It has recently been shown that FDTS catalysis does not rely on an enzymatic nucleophile and that the proposed reaction intermediates are not covalently bound to the enzyme during catalysis, an important distinction from the human TSase. Here we report the chemical trapping, isolation, and identification of a derivative of such an intermediate in the FDTS-catalyzed reaction. The chemically modified reaction intermediate is consistent with currently proposed FDTS mechanisms that do not involve an enzymatic nucleophile, and it has never been observed during any other TSase reaction. These findings establish the timing of the methylene transfer during FDTS catalysis. The presented methodology provides an important experimental tool for further studies of FDTS, which may assist efforts directed toward the rational design of inhibitors as leads for future antibiotics.
Polymer-bound oxathiaphospholane: A solid-phase reagent for regioselective monothiophosphorylation and monophosphorylation of unprotected nucleosides and carbohydrates
Ahmadibeni, Yousef,Parang, Keykavous
, p. 1955 - 1958 (2005)
(Chemical Equation Presented) Two polymers bound to N,N-diisopropylamino-1, 3,2-oxathiaphospholane were reacted with unprotected carbohydrates and nucleosides in the presence of 1H-tetrazole, followed by oxidation with tert-butyl hydroperoxide or sulfurization with Beaucage's reagent. The 1,3,2-oxathiaphospholane ring-opening with 3-hydroxypropionitrile, followed by treatment with DBU, afforded the corresponding monophosphate and monothiophosphate derivatives, respectively, through the elimination of polymer-bound ethylene episulfide. Reactions using this strategy offer the advantages of high regioselectivity, monosubstitution, and facile isolation and recovery of products.
Effect of C-terminal of human cytosolic thymidine kinase (TK1) on in vitro stability and enzymatic properties
Zhu,Harlow,Berenstein,Munch-Petersen,Munch-Petersen
, p. 1185 - 1188 (2006)
Thymidine kinase (TK1) is a key enzyme in the salvage pathway of nucleotide metabolism and catalyzes the first rate-limiting step in the synthesis of dTTP, transfer of a gamma-phosphate group from a nucleoside triphosphate to the 5′-hydroxyl group of thymidine, thus forming dTMP. TK1 is cytosolic and its activity fluctuates during cell cycle coinciding with the DNA synthesis rate and disappears during mitosis. This fluctuation is important for providing a balanced supply of dTTP for DNA replication. The cell cycle specific activity of TK1 is regulated at the transcriptional level, but posttranslational mechanisms seem to play an important role for the level of functional TK1 protein as well. Thus, the C-terminal of TK1 is known to be essential for the specific degradation of the enzyme at the G2/M phase. In this work, we have studied the effect of deletion of the C-terminal 20, 40, and 44 amino acids of TK1 on in vitro stability, oligomerization, and enzyme kinetics. We found that deletion of the C-terminal fold markedly increased the stability as well as the catalytic activity. Copyright Taylor & Francis Group, LLC.
Enzyme Activation with a Synthetic Catalytic Co-enzyme Intermediate: Nucleotide Methylation by Flavoenzymes
Bou-Nader, Charles,Cornu, David,Guerineau, Vincent,Fogeron, Thibault,Fontecave, Marc,Hamdane, Djemel
, p. 12523 - 12527 (2017)
To facilitate production of functional enzymes and to study their mechanisms, especially in the complex cases of coenzyme-dependent systems, activation of an inactive apoenzyme preparation with a catalytically competent coenzyme intermediate is an attractive strategy. This is illustrated with the simple chemical synthesis of a flavin-methylene iminium compound previously proposed as a key intermediate in the catalytic cycle of several important flavoenzymes involved in nucleic acid metabolism. Reconstitution of both flavin-dependent RNA methyltransferase and thymidylate synthase apoproteins with this synthetic compound led to active enzymes for the C5-uracil methylation within their respective transfer RNA and dUMP substrate. This strategy is expected to be of general application in enzymology.
Enzymatic Production of Non-Natural Nucleoside-5′-Monophosphates by a Thermostable Uracil Phosphoribosyltransferase
del Arco, Jon,Acosta, Javier,Pereira, Humberto M.,Perona, Almudena,Lokanath, Neratur K.,Kunishima, Naoki,Fernández-Lucas, Jesús
, p. 439 - 448 (2018)
The use of enzymes as biocatalysts applied to synthesis of modified nucleoside-5′-monophosphates (NMPs) is an interesting alternative to traditional multistep chemical methods which offers several advantages, such as stereo-, regio-, and enantioselectivity, simple downstream processing, and mild reaction conditions. Herein we report the recombinant expression, production, and purification of uracil phosphoribosyltransferase from Thermus themophilus HB8 (TtUPRT). The structure of TtUPRT has been determined by protein crystallography, and its substrate specificity and biochemical characteristics have been analyzed, providing new structural insights into the substrate-binding mode. Biochemical characterization of the recombinant protein indicates that the enzyme is a homotetramer, with activity and stability across a broad range of temperatures (50–80 °C), pH (5.5–9) and ionic strength (0–500 mm NaCl). Surprisingly, TtUPRT is able to recognize several 5 and 6-substituted pyrimidines as substrates. These experimental results suggest TtUPRT could be a valuable biocatalyst for the synthesis of modified NMPs.
Enzymatic phosphorylation of unnatural nucleosides
Wu, Yiqin,Fa, Ming,Tae, Eunju Lee,Schultz, Peter G.,Romesberg, Floyd E.
, p. 14626 - 14630 (2002)
In an effort to expand the genetic alphabet, a number of unnatural, predominantly hydrophobic, nucleoside analogues have been developed which pair selectively in duplex DNA and during enzymatic synthesis. Significant progress has been made toward the efficient in vitro replication of DNA containing these base pairs. However, the in vivo expansion of the genetic alphabet will require that the unnatural nucleoside triphosphates be available within the cell at sufficient concentrations for DNA replication. We report our initial efforts toward the development of an unnatural in vivo nucleoside phosphorylation pathway that is based on nucleoside salvage enzymes. The first step of this pathway is catalyzed by the D. melanogaster nucleoside kinase, which catalyzes the phosphorylation of nucleosides to the corresponding monophosphates. We demonstrate that each unnatural nucleoside is phosphorylated with a rate that should be sufficient for the in vivo replication of DNA.
