68-94-0Relevant articles and documents
The inhibitory effect of citrus flavonoids naringenin and hesperetin against purine nucleoside phosphorylase: Spectroscopic, atomic force microscopy and molecular modeling studies
Gong, Deming,Lv, Xingang,Ren, Er-Fang,Wang, Lang-Hong,Wang, Qilei
, (2020)
In this work, the inhibitory effect of two citrus flavonoids naringenin and hesperetin on human purine nucleoside phosphorylase (hPNP) and their binding mechanism were evaluated. Results from enzymatic kinetics revealed that naringenin and hesperetin reversibly inhibited hPNP via a mixed-type manner with IC50 values of 4.83 × 10?4 M and 5.32 × 10?4 M, respectively. Analysis of molecular modeling revealed that both naringenin and hesperetin bound directly into the active site by generating multiple forces including hydrogen bonding, π–π and π-Alkyl interactions with His64, Glu201, Ser220, His257, Phe200 and Val217 residues of hPNP, which caused the inhibition of hPNP activity. Moreover, conformational analysis by three-dimension fluorescence, circular dichroism and atomic force microscopy revealed that the binding of naringenin and hesperetin to hPNP induced changes in the microenvironment, secondary structure and morphology of hPNP. These results suggested that occupying the active site and enzymatic conformational perturbation induced by naringenin and hesperetin are the main reasons for reducing the inhibition of hPNP activity, which would be helpful in understanding the inhibitory mechanism of naringenin and hesperetin against hPNP.
Ribocation Transition State Capture and Rebound in Human Purine Nucleoside Phosphorylase
Ghanem, Mahmoud,Murkin, Andrew S.,Schramm, Vern L.
, p. 971 - 979 (2009)
Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of 6-oxy-purine nucleosides to the corresponding purine base and α-D-ribose 1-phosphate. Its genetic loss causes a lethal T cell deficiency. The highly reactive ribocation transition state
Calcium-stimulated guanosine-inosine nucleosidase from yellow lupin (Lupinus luteus)
Szuwart, Maciej,Starzynska, Elzbieta,Pietrowska-Borek, Malgorzata,Guranowski, Andrzej
, p. 1476 - 1485 (2006)
Guanosine-inosine-preferring nucleoside N-ribohydrolase has been purified to homogeneity from yellow lupin (Lupinus luteus) seeds by ammonium sulfate fractionation, ion-exchange chromatography and gel filtration. The enzyme functions as a monomeric, 80 kDa polypeptide, most effectively between pH 4.7 and 5.5. Of various mono- and divalent cations tested, Ca2+ appeared to stimulate enzyme activity. The nucleosidase was activated 6-fold by 2 mM exogenous CaCl2 or Ca(NO3)2, with Ka = 0.5 mM (estimated for CaCl2). The Km values estimated for guanosine and inosine were 2.7 ± 0.3 μM. Guanosine was hydrolyzed 12% faster than inosine while adenosine and xanthosine were poor substrates. 2′-Deoxyguanosine, 2′-deoxyinosine, 2′-methylguanosine, pyrimidine nucleosides and 5′-GMP were not hydrolyzed. However, the enzyme efficiently liberated the corresponding bases from synthetic nucleosides, such as 1-methylguanosine, 7-methylguanosine, 1-N2-ethenoguanosine and 1-N2-isopropenoguanosine, but hydrolyzed poorly the ribosides of 6-methylaminopurine and 2,6-diaminopurine. MnCl2 or ZnCl2 inhibited the hydrolysis of guanosine with I50 ≈ 60 μM. Whereas 2′-deoxyguanosine, 2′-methylguanosine, adenosine, as well as guanine were competitive inhibitors of this reaction (Ki values were 1.5, 3.6, 21 and 9.7 μM, respectively), hypoxanthine was a weaker inhibitor (Ki = 64 μM). Adenine, ribose, 2-deoxyribose, 5′-GMP and pyrimidine nucleosides did not inhibit the enzyme. The guanosine-inosine hydrolase activity occurred in all parts of lupin seedlings and in cotyledons it increased up to 5-fold during seed germination, reaching maximum in the third/fourth day. The lupin nucleosidase has been compared with other nucleosidases.
Enzymatic deamination of the epigenetic base N-6-methyladenine
Kamat, Siddhesh S.,Fan, Hao,Sauder, J. Michael,Burley, Stephen K.,Shoichet, Brian K.,Sali, Andrej,Raushel, Frank M.
, p. 2080 - 2083 (2011)
Two enzymes of unknown function from the amidohydrolase superfamily were discovered to catalyze the deamination of N-6-methyladenine to hypoxanthine and methyl amine. The methylation of adenine in bacterial DNA is a common modification for the protection of host DNA against restriction endonucleases. The enzyme from Bacillus halodurans, Bh0637, catalyzes the deamination of N-6-methyladenine with a kcat of 185 s-1 and a k cat/Km of 2.5 x 106 M-1 s -1. Bh0637 catalyzes the deamination of N-6-methyladenine 2 orders of magnitude faster than adenine. A comparative model of Bh0637 was computed using the three-dimensional structure of Atu4426 (PDB code: 3NQB) as a structural template and computational docking was used to rationalize the preferential utilization of N-6-methyladenine over adenine. This is the first identification of an N-6-methyladenine deaminase (6-MAD).
Localization of purine metabolizing enzymes in bovine brain microvessel endothelial cells: An enzymatic blood-brain barrier for dideoxynucleosides?
Johnson, Mark D.,Andersen, Bradley D.
, p. 1881 - 1886 (1996)
Purpose. The specific activities of the purine and pyrimidine metabolizing enzymes, purine nucleoside phosphorylase (PNP), adenosine deaminase (ADA) and cytidine deaminase (CDA) were determined in bovine brain microvessel endothelial cells, (BBMECs), whole cerebral tissue and erythrocytes. In addition, the substrate specificities (K(m) and V(max)) of purified calf spleen PNP for inosine and 2',3'-dideoxyinosine (ddI) and of purified calf intestinal ADA for 2',3'-dideoxyadenosine (ddA), 6-chloro-2',3'-dideoxypurine (6-Cl-ddP), and 2'-β-fluoro-2',3'-dideoxyadenosine (F-ddA) have been explored. Methods. BBMECs were isolated from bovine cerebral cortex by a two step enzymatic dispersion treatment followed by centrifugation over 50% Percoll density gradients. Activities of alkaline phosphatase, γ-glutamyl transpeptidase, ADA, PNP and CDA were determined in various tissue homogenates (cerebral cortex, BBMECs and erythrocytes). Enzyme kinetic studies were also conducted using commercially available enzymes and several nucleoside analogs of interest. Results. The activities of ADA and PNP were 42-fold and 247-fold higher in the cerebral microvessels than in the cerebral cortex, respectively, while there was no detectable CDA activity in the microvessel fraction and very little overall activity in the cortex. Conclusions. ADA and PNP may serve as an enzymatic blood-brain barrier for some of the anti-HIV dideoxynucleosides. Simulations of brain availability for ddI, ddA, 6-Cl-ddP, and FddA demonstrated that the quantitative significance of enzyme localization may vary dramatically, however, depending on the membrane permeability of the drug and its bioconversion rate constant within the endothelial cell.
Phloroglucinols Inhibit Chemical Mediators and Xanthine Oxidase, and Protect Cisplatin-Induced Cell Death by Reducing Reactive Oxygen Species in Normal Human Urothelial and Bladder Cancer Cells
Lin, Kai-Wei,Huang, A.-Mei,Tu, Huang-Yao,Weng, Jing-R.U.,Hour, Tzyh-Chyuan,Wei, Bai-Luh,Yang, Shyh-Chyun,Wang, Jih-Pyang,Pu, Yeong-Shiau,Lin, Chun-Nan
, p. 8782 - 8787 (2009)
Phloroglucinols, garcinielliptones HA-HE (1-5), and C (6) were studied in vitro for their inhibitory effects on chemical mediators released from mast cells, neutrophils, and macrophages. Compound 6 revealed significant inhibitory effect on release of lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Compounds 3, 4, and 6 showed significant inhibitory effects on superoxide anion generation in rat neutrophils stimulated with (fMLP)/(CB), while compounds 1 and 5 revealed inhibitory effects on tumor necrosis factor-α (TNF-α) formation in macrophages stimulated with lipopolysaccharide (LPS). Compounds 1 and 3-6 showed inhibitory effects on xanthine oxidase (XO) and could inhibit the DNA breakage caused by O2-.. Treatment of NTUB1 with 2 to 60 μM compound 3 and 5 μM cisplatin and SV-HUC1 with 9 to 60 μM 3 and 5 μM cisplatin, respectively, resulted in an increase of viability of cells. These results indicated that compounds 1 and 3-6 showed anti-inflammatory effects and antioxidant activities. Compound 3 mediates through the suppression of XO activity and reduction of reactive oxygen species (ROS), and protection of subsequent cell death.
Synthetic method of nitric acid catalyzed hypoxanthine derivative
-
Paragraph 0027-0036, (2021/10/11)
The invention discloses a synthetic method of a nitric acid catalytic hypoxanthine derivative, and belongs to the technical field of pharmaceutical chemistry. 6 - Chloropurine derivatives were mixed with a solvent, a catalytic amount of nitric acid heating reaction was added, and acid generated in the reaction was neutralized, and the solvent was removed under reduced pressure to obtain a hypoxanthine derivative. The hypoxanthine derivative obtained by the method is low in cost, high in purity and good in substrate adaptability; various impurities in a traditional method are removed; separation and purification are convenient; and the reliability of the quality of the hypoxanthine derivative is improved.
Thermodynamic Reaction Control of Nucleoside Phosphorolysis
Kaspar, Felix,Giessmann, Robert T.,Neubauer, Peter,Wagner, Anke,Gimpel, Matthias
supporting information, p. 867 - 876 (2020/01/24)
Nucleoside analogs represent a class of important drugs for cancer and antiviral treatments. Nucleoside phosphorylases (NPases) catalyze the phosphorolysis of nucleosides and are widely employed for the synthesis of pentose-1-phosphates and nucleoside analogs, which are difficult to access via conventional synthetic methods. However, for the vast majority of nucleosides, it has been observed that either no or incomplete conversion of the starting materials is achieved in NPase-catalyzed reactions. For some substrates, it has been shown that these reactions are reversible equilibrium reactions that adhere to the law of mass action. In this contribution, we broadly demonstrate that nucleoside phosphorolysis is a thermodynamically controlled endothermic reaction that proceeds to a reaction equilibrium dictated by the substrate-specific equilibrium constant of phosphorolysis, irrespective of the type or amount of NPase used, as shown by several examples. Furthermore, we explored the temperature-dependency of nucleoside phosphorolysis equilibrium states and provide the apparent transformed reaction enthalpy and apparent transformed reaction entropy for 24 nucleosides, confirming that these conversions are thermodynamically controlled endothermic reactions. This data allows calculation of the Gibbs free energy and, consequently, the equilibrium constant of phosphorolysis at any given reaction temperature. Overall, our investigations revealed that pyrimidine nucleosides are generally more susceptible to phosphorolysis than purine nucleosides. The data disclosed in this work allow the accurate prediction of phosphorolysis or transglycosylation yields for a range of pyrimidine and purine nucleosides and thus serve to empower further research in the field of nucleoside biocatalysis. (Figure presented.).
Structural and biochemical characterization of the nucleoside hydrolase from C. elegans reveals the role of two active site cysteine residues in catalysis
Singh, Ranjan Kumar,Steyaert, Jan,Versées, Wim
, p. 985 - 996 (2017/05/01)
Nucleoside hydrolases (NHs) catalyze the hydrolysis of the N-glycoside bond in ribonucleosides and are found in all three domains of life. Although in parasitic protozoa a role in purine salvage has been well established, their precise function in bacteria and higher eukaryotes is still largely unknown. NHs have been classified into three homology groups based on the conservation of active site residues. While many structures are available of representatives of group I and II, structural information for group III NHs is lacking. Here, we report the first crystal structure of a purine-specific nucleoside hydrolase belonging to homology group III from the nematode Caenorhabditis elegans (CeNH) to 1.65? resolution. In contrast to dimeric purine-specific NHs from group II, CeNH is a homotetramer. A cysteine residue that characterizes group III NHs (Cys253) structurally aligns with the catalytic histidine and tryptophan residues of group I and group II enzymes, respectively. Moreover, a second cysteine (Cys42) points into the active site of CeNH. Substrate docking shows that both cysteine residues are appropriately positioned to interact with the purine ring. Site-directed mutagenesis and kinetic analysis proposes a catalytic role for both cysteines residues, with Cys253 playing the most prominent role in leaving group activation.
The Chemoenzymatic Synthesis of 2-Chloro- and 2-Fluorocordycepins
Denisova, Alexandra O.,Tokunova, Yulia A.,Fateev, Ilja V.,Breslav, Alexandra A.,Leonov, Vladimir N.,Dorofeeva, Elena V.,Lutonina, Olga I.,Muzyka, Inessa S.,Esipov, Roman S.,Kayushin, Alexey L.,Konstantinova, Irina D.,Miroshnikov, Anatoly I.,Stepchenko, Vladimir A.,Mikhailopulo, Igor A.
, p. 4853 - 4860 (2017/10/06)
Two approaches to the chemoenzymatic synthesis of 2-fluorocordycepin and 2-chlorocordycepin were studied: (i) the use of 3′-deoxyadenosine (cordycepin) and 3′-deoxyinosine (3′dIno) as donors of 3-deoxy- d -ribofuranose in the transglycosylation of 2-fluoro- (2F Ade) and 2-chloroadenine (2Cl Ade) catalyzed by the recombinant E. coli purine nucleoside phosphorylase (PNP), and (ii) the use of 2-fluoroadenosine and 3′-deoxyinosine as substrates of the cross-glycosylation and PNP as a biocatalyst. An efficient method for 3′-deoxyinosine synthesis starting from inosine was developed. However, the very poor solubility of 2Cl Ade and 2F Ade is the limiting factor of the first approach. The second approach enables this problem to be overcome and it appears to be advantageous over the former approach from the viewpoint of practical synthesis of the title nucleosides. The 3-deoxy-α- d -ribofuranose-1-phosphate intermediary formed in the 3′dIno phosphorolysis by PNP was found to be the weak and marginal substrate of E. coli thymidine (TP) and uridine (UP) phosphorylases, respectively. Finally, one-pot cascade transformation of 3-deoxy- d -ribose in cordycepin in the presence of adenine and E. coli ribokinase, phosphopentomutase, and PNP was tested and cordycepin formation in ca. 3.4% yield was proved.
