17039-17-7Relevant academic research and scientific papers
The role of phosphate in the action of thymidine phosphorylase inhibitors: Implications for the catalytic mechanism
Jain, Harsh V.,Rasheed, Roshni,Kalman, Thomas I.
, p. 1648 - 1651 (2010)
The design and synthesis of 5-fluoro-6-[(2-aminoimidazol-1-yl)methyl]uracil (AIFU), a potent inhibitor of thymidine phosphorylase (TP) with Ki-values of 11 nM (ecTP) and 17 nM (hTP), are described. Kinetic studies established that the type of inhibition of TP by AIFU is uncompetitive with respect to inorganic phosphate (or arsenate). The results obtained suggest that AIFU and other zwitterionic thymine analog inhibitors of TP act as transition state analogs, mimicking the anionic thymine leaving group, consistent with an SN2-type catalytic mechanism, and anchored by their protonated side chains to the enzyme-bound phosphate by electrostatic and H-bonding interactions.
Substrate specificity of thymidine phosphorylase of E. coli: Role of hydroxyl groups
Panova, Natalya G.,Alexeev, Cyril S.,Polyakov, Konstantin M.,Gavryushov, Sergei A.,Kritzyn, Anatoliy M.,Mikhailov, Sergey N.
, p. 1211 - 1214 (2008)
Substrate specificity of E. coli thymidine phosphorylase to pyrimidine nucleoside modified at 5′-, 3′-, and 2′-positions of sugar moiety has been studied. Equilibrium (Keq) and kinetics constants of phosphorolysis reaction of nucleosides were measured. Th
The Peculiar Case of the Hyper-thermostable Pyrimidine Nucleoside Phosphorylase from Thermus thermophilus**
Kaspar, Felix,Neubauer, Peter,Kurreck, Anke
, p. 1385 - 1390 (2021/01/29)
The poor solubility of many nucleosides and nucleobases in aqueous solution demands harsh reaction conditions (base, heat, cosolvent) in nucleoside phosphorylase-catalyzed processes to facilitate substrate loading beyond the low millimolar range. This, in turn, requires enzymes that can withstand these conditions. Herein, we report that the pyrimidine nucleoside phosphorylase from Thermus thermophilus is active over an exceptionally broad pH (4–10), temperature (up to 100 °C) and cosolvent space (up to 80 % (v/v) nonaqueous medium), and displays tremendous stability under harsh reaction conditions with predicted total turnover numbers of more than 106 for various pyrimidine nucleosides. However, its use as a biocatalyst for preparative applications is critically limited due to its inhibition by nucleobases at low concentrations, which is unprecedented among nonspecific pyrimidine nucleoside phosphorylases.
Characterization of pyrimidine nucleoside phosphorylase of Mycoplasma hyorhinis: Implications for the clinical efficacy of nucleoside analogues
Vande Voorde, Johan,Gago, Federico,Vrancken, Kristof,Liekens, Sandra,Balzarini, Jan
experimental part, p. 113 - 123 (2012/10/23)
In the present paper we demonstrate that the cytostatic and antiviral activity of pyrimidine nucleoside analogues is markedly decreased by a Mycoplasma hyorhinis infection and show that the phosphorolytic activity of the mycoplasmas is responsible for this. Since mycoplasmas are (i) an important cause of secondary infections in immunocompromised (e.g. HIV infected) patients and (ii) known to preferentially colonize tumour tissue in cancer patients, catabolic mycoplasma enzymesmay compromise efficient chemotherapy of virus infections and cancer. In the genome of M. hyorhinis, a TP (thymidine phosphorylase) gene has been annotated. This gene was cloned, expressed in Escherichia coli and kinetically characterized. Whereas the mycoplasma TP efficiently catalyses the phosphorolysis of thymidine (Km = 473 μM) and deoxyuridine (Km = 578 μM), it prefers uridine (K m =92 μM) as a substrate. Our kinetic data and sequence analysis revealed that the annotated M. hyorhinis TP belongs to the NP (nucleoside phosphorylase)-II class PyNPs (pyrimidine NPs), and is distinct from the NP-II class TP and NPI class UPs (uridine phosphorylases). M. hyorhinis PyNP also markedly differs from TP and UP in its substrate specificity towards therapeutic nucleoside analogues and susceptibility to clinically relevant drugs. Several kinetic properties of mycoplasma PyNP were explained by in silico analyses. The Authors Journal compilation
PHOSPHORAMIDATE DERIVATIVES OF 5 - FLUORO - 2 ' - DEOXYURIDINE FOR USE IN THE TREATMENT OF CANCER
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Page/Page column 66-67, (2012/09/21)
Phosphoramidate derivatives of 5-fluoro-2'-deoxyuridine are disclosed for use in the treatment of cancer, especially in the treatment of cancer where the patient shows resistance, for example, in a patient with cells with a lowered level of nucleoside transporter proteins and/or with nucleoside kinase-deficient cells and/or with mycoplasma-infected cells and/or with cells with a raised level of thymidylate synthase.
Transition-state analysis of Trypanosoma cruzi uridine phosphorylase- catalyzed arsenolysis of uridine
Silva, Rafael G.,Vetticatt, Mathew J.,Merino, Emilio F.,Cassera, Maria B.,Schramm, Vern L.
experimental part, p. 9923 - 9931 (2011/08/10)
Uridine phosphorylase catalyzes the reversible phosphorolysis of uridine and 2′-deoxyuridine to generate uracil and (2-deoxy)ribose 1-phosphate, an important step in the pyrimidine salvage pathway. The coding sequence annotated as a putative nucleoside phosphorylase in the Trypanosoma cruzi genome was overexpressed in Escherichia coli, purified to homogeneity, and shown to be a homodimeric uridine phosphorylase, with similar specificity for uridine and 2′-deoxyuridine and undetectable activity toward thymidine and purine nucleosides. Competitive kinetic isotope effects (KIEs) were measured and corrected for a forward commitment factor using arsenate as the nucleophile. The intrinsic KIEs are: 1′-14C = 1.103, 1,3-15N 2 = 1.034, 3-15N = 1.004, 1-15N = 1.030, 1′-3H = 1.132, 2′-2H = 1.086, and 5′-3H2 = 1.041 for this reaction. Density functional theory was employed to quantitatively interpret the KIEs in terms of transition-state structure and geometry. Matching of experimental KIEs to proposed transition-state structures suggests an almost synchronous, S N2-like transition-state model, in which the ribosyl moiety possesses significant bond order to both nucleophile and leaving groups. Natural bond orbital analysis allowed a comparison of the charge distribution pattern between the ground-state and the transition-state models.
Transition state analysis of thymidine hydrolysis by human thymidine phosphorylase
Schwartz, Phillip A.,Vetticatt, Mathew J.,Schramm, Vern L.
supporting information; experimental part, p. 13425 - 13433 (2010/12/19)
Human thymidine phosphorylase (hTP) is responsible for thymidine (dT) homeostasis, and its action promotes angiogenesis. In the absence of phosphate, hTP catalyzes a slow hydrolytic depyrimidination of dT yielding thymine and 2-deoxyribose (dRib). Its transition state was characterized using multiple kinetic isotope effect (KIE) measurements. Isotopically enriched thymidines were synthesized enzymatically from glucose or (deoxy)ribose, and intrinsic KIEs were used to interpret the transition state structure. KIEs from [1′- 14C]-, [1-15N]-, [1′-3H]-, [2′R-3H]-, [2′S-3H]-, [4′- 3H]-, and [5′-3H]dTs provided values of 1.033 ± 0.002, 1.004 ± 0.002, 1.325 ± 0.003, 1.101 ± 0.004, 1.087 ± 0.005, 1.040 ± 0.003, and 1.033 ± 0.003, respectively. Transition state analysis revealed a stepwise mechanism with a 2-deoxyribocation formed early and a higher energetic barrier for nucleophilic attack of a water molecule on the high energy intermediate. An equilibrium exists between the deoxyribocation and reactants prior to the irreversible nucleophilic attack by water. The results establish activation of the thymine leaving group without requirement for phosphate. A transition state constrained to match the intrinsic KIEs was found using density functional theory. An active site histidine (His116) is implicated as the catalytic base for activation of the water nucleophile at the rate-limiting transition state. The distance between the water nucleophile and the anomeric carbon (rC-O) is predicted to be 2.3 A at the transition state. The transition state model predicts that deoxyribose adopts a mild 3′-endo conformation during nucleophilic capture. These results differ from the concerted bimolecular mechanism reported for the arsenolytic reaction (Birck, M. R.; Schramm, V. L. J. Am. Chem. Soc. 2004, 126, 2447-2453).
Gene therapy of cancer: activation of nucleoside prodrugs with e. colipurine nucleoside phosphorylase
Secrist III, John A.
, p. 745 - 757 (2007/10/03)
During the last few years, many gene therapy strategies have been developed for various disease targets. The development of anticancer gene therapy strategies to selectively generate cytotoxic nucleoside or nucleotide analogs is an attractive goal. One such approach involves the delivery of herpes simplex virus thymidine kinase followed by the acyclic nucleoside analog ganciclovir. We have developed another gene therapy methodology for the treatment of cancer that has several significant attributes. Specifically, our approach involves the delivery of E. coli purine nucleoside phosphorylase, followed by treatment with a relatively non-toxic nucleoside prodrug that is cleaved by the enzyme to a toxic compound. .This presentation describes the concept, details our search for suitable prodrugs, and summarizes the current biological data. Copyright
