- Cloning, expression and biochemical characterization of xanthine and adenine phosphoribosyltransferases from Thermus thermophilus HB8
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Purine phosphoribosyltransferases, purine PRTs, are essential enzymes in the purine salvage pathway of living organisms. They are involved in the formation of C-N glycosidic bonds in purine nucleosides-5′-monophosphate (NMPs) through the transfer of the 5-phosphoribosyl group from 5-phospho-α-D-ribosyl-1-pyrophosphate (PRPP) to purine nucleobases in the presence of Mg2+. Herein, we report a simple and thermostable process for the one-pot, one-step synthesis of some purine NMPs using xanthine phosphoribosyltransferase, XPRT or adenine phosphoribosyltransferase, APRT2, from Thermus thermophilus HB8. In this sense, the cloning, expression and purification of TtXPRT and TtAPRT2 is described for the first time. Both genes, xprt and aprt2 were expressed as his-tagged enzymes in E. coli BL21(DE3) and purified by a heat-shock treatment, followed by Ni-affinity chromatography and a final, polishing gel-filtration chromatography. Biochemical characterization revealed TtXPRT as a tetramer and TtAPRT2 as a dimer. In addition, both enzymes displayed a strong temperature dependence (relative activity >75% in a temperature range from 70 to 90 °C), but they also showed very different behaviour under the influence of pH. While TtXPRT is active in a pH range from 5 to 7, TtAPRT2 has a high dependence of alkaline conditions, showing highest activity values in a pH range from 8 to 10. Finally, substrate specificity studies were performed in order to explore their potential as industrial biocatalyst for NMPs synthesis.
- Del Arco, Jon,Martinez, María,Donday, Manuel,Clemente-Suarez, Vicente Javier,Fernández-Lucas, Jesús
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- Structure-activity relationships for the binding of ligands to xanthine or guanine phosphoribosyl-transferase from Toxoplasma gondii
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Preliminary characterization of Toxoplasma gondii phosphoribosyltransferase activity towards purine nucleobases indicates that there are at least two enzymes present in these parasites. One enzyme uses hypoxanthine, guanine, and xanthine as substrates, while a second enzyme uses only adenine. Furthermore, competition experiments using the four possible substrates suggest that there may be a third enzyme that uses xanthine. Therefore, sixty-eight purine analogues and thirteen related derivatives were evaluated as ligands of T. gondii phosphoribosyltransferase, using xanthine or guanine as substrates, by examining their ability to inhibit these reactions in vitro. Inhibition was quantified by determining apparent K(i) values for compounds that inhibited these activities by greater than 10% at a concentration of 0.9 mM. On the basis of these data, a structure-activity relationship for the binding of ligands to these enzymes was formulated using hypoxanthine (6-oxopurine) as a reference compound. It was concluded that the following structural features of purine analogues are required or strongly preferred for binding to both enzymes: (1) a pyrrole-type nitrogen (lactam form) at the 1-position; (2) a methine (=CH-), a pyridine type nitrogen (=N-), or an exocyclic amino or oxo group at the 2-position; (3) no exocyclic substituents at the 3-position; (4) an exocyclic oxo or thio group in the one or thione tautomeric form at the 6-position; (5) a pyridine-type nitrogen (=N-) or a methine group at the 7-position; (6) a methine group at the 8-position; (7) a pyrrole-type nitrogen or a carbon at the 9-position; and (8) no exocyclic substituents at the 9-position. These findings provide the basis for the rational design of additional ligands of hypoxanthine, guanine, and xanthine phosphoribosyltransferase activities in T. gondii.
- Naguib,Iltzsch,El Kouni,Panzica,El Kouni
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- Phosphorylation of guanosine using guanosine-inosine kinase from Exiguobacterium acetylicum coupled with ATP regeneration.
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Guanosine 5'-monophosphate (5'-GMP) and inosine 5'-monophosphate (5'-IMP) are widely used as flavor enhancers. Recently, a novel process for 5'-IMP production by phosphorylation of inosine using guanosine-inosine kinase coupled with ATP regeneration was reported. In this study, we demonstrated the practical possibility of producing 5'-GMP by phosphorylation of guanosine using a guanosine-inosine kinase from Exiguobacterium acetylicum coupled with ATP regeneration.
- Kawasaki,Usuda,Shimaoka,Utagawa
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- Amplification of adenine phosphoribosyltransferase suppresses the conditionally lethal growth and virulence phenotype of Leishmania donovani mutants lacking both hypoxanthine-guanine and xanthine phosphoribosyltransferases
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Leishmania donovani cannot synthesize purines de novo and obligatorily scavenge purines from the host. Previously, we described a conditional lethal Δhgprt/Δxprt mutant of L. donovani (Boitz, J. M., and Ullman, B. (2006) J. Biol. Chem. 281, 16084-16089) that establishes that L. donovani salvages purines primarily through hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and xanthine phosphoribosyltransferase (XPRT). Unlike wild type L. donovani, the Δhgprt/Δxprt knock-out cannot grow on 6-oxypurines and displays an absolute requirement for adenine or adenosine and 2′-deoxycoformycin, an inhibitor of parasite adenine aminohydrolase activity. Here, we demonstrate that the ability of Δhgprt/Δxprt parasites to infect mice was profoundly compromised. Surprisingly, mutant parasites that survived the initial passage through mice partially regained their virulence properties, exhibiting a >10-fold increase in parasite burden in a subsequent mouse infection. To dissect the mechanism by which Δhgprt/Δxprt parasites persisted in vivo, suppressor strains that had regained their capacity to grow under restrictive conditions were cloned from cultured Δhgprt/Δxprt parasites. The ability of these suppressor clones to grow in and metabolize 6-oxypurines could be ascribed to a marked amplification and overexpression of the adenine phosphoribosyltransferase (APRT) gene. Moreover, transfection of Δhgprt/Δxprt cells with an APRT episome recapitulated the suppressor phenotype in vitro and enabled growth on 6-oxypurines. Biochemical studies further showed that hypoxanthine, unexpectedly, was an inefficient substrate for APRT, evidence that could account for the ability of the suppressors to metabolize hypoxanthine. Subsequent analysis implied that APRT amplification was also a potential contributory mechanism by which Δhgprt/Δxprt parasites displayed persistence and increased virulence in mice.
- Boitz, Jan M.,Ullman, Buddy
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- Improving the pyrophosphate-inosine phosphotransferase activity of Escherichia blattae acid phosphatase by sequential site-directed mutagenesis
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Escherichia blattae acid phosphatase/phosphotransferase (EB-AP/PTase) exhibits C-5′-position selective pyrophosphate-nucleoside phosphotransferase activity in addition to its intrinsic phosphatase. Improvement of its phosphotransferase activity was investigated by sequential site-directed mutagenesis. By comparing the primary structures of higher 5′-inosinic acid (5′-IMP) productivity and lower 5′-IMP productivity acid phosphatase/phosphotransferase, candidate residues of substitution were selected. Then a total of 11 amino acid substitutions were made with sequential substitutions. As the number of substituted amino acid residues increased, the 5′-IMP productivity of the mutant enzyme increased, and the activity of the 11 mutant phosphotransferases of EB-AP/PTase reached the same level as that of Morganella morganii AP/PTase. This result shows that Leu63, Ala65, Glu66, Asn69, Ser71, Asp116, Thr135, and Glu136, whose relevance was not directly established by structural analysis alone, also plays an important role in the phosphotransferase activity of EB-AP/PTase.
- Mihara, Yasuhiro,Ishikawa, Kohki,Suzuki, Ei-Ichiro,Asano, Yasuhisa
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- Phosphorylation of ribavirin and viramidine by adenosine kinase and cytosolic 5′-nucleotidase II: Implications for ribavirin metabolism in erythrocytes
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Many nucleoside analog drugs, such as ribavirin and viramidine, are activated or metabolized in vivo through 5′-phosphorylation. In this report, we determined the steady-state kinetic parameters for 5′-monophosphorylation of ribavirin and viramidine by adenosine kinase. The apparent Km for ribavirin is 540 μM, and kcat is 1.8 min-1. Its catalytic efficiency of 3.3 × 10-3 min-1 is 1,200-fold lower than that of adenosine. In contrast to the common belief that ribavirin is exclusively phosphorylated by adenosine kinase, cytosolic 5′-nucleotidase II was found to catalyze ribavirin phosphorylation in vitro. The reaction is optimally stimulated by the physiological concentration of ATP or 2,3-bisphosphoglycerate. In phosphate-buffered saline plus ATP and 2,3-bisphosphoglycerate, the apparent Km for ribavirin is 88 μM, and kcat is 4.0 min -1. These findings suggest that cytosolic 5′-nucleotidase II may be involved in ribavirin phosphorylation in vivo. Like ribavirin, viramidine was found to be phosphorylated by either adenosine kinase or cytosolic 5′-nucleotidase II, albeit with a much lower activity. The catalytic efficiency for viramidine phosphorylation is 10- to 330-fold lower than that of ribavirin, suggesting that other nucleoside kinase(s) may be involved in viramidine phosphorylation in vivo. Both ribavirin and viramidine are not phosphorylated by deoxycytidine kinase and uridine-cytidine kinase. The coincidence of presence of high concentrated 2,3-bisphosphoglycerate in erythrocytes suggests that cytosolic 5′-nucleotidase II could play an important role in phosphorylating ribavirin and contribute to anabolism of ribavirin triphosphate in erythrocytes. Elucidation of ribavirin and viramidine phosphorylation mechanism should shed light on their in vivo metabolism, especially the ribavirin-induced hemolytic anemia in erythrocytes. Copyright
- Wu, Jim Zhen,Larson, Gary,Walker, Heli,Shim, Jae Hoon,Hong, Zhi
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- Highly regioselective methylation of inosine nucleotide: an efficient synthesis of 7-methylinosine nucleotide
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A facile, straightforward, reliable, and an efficient chemical synthesis of inosine nucleotides such as 7-methylinosine 5′-O-monophosphate, 7-methylinosine 5′-O-diphosphate, and 7-methylinosine 5′-O-triphosphate, starting from the corresponding inosine nucleotide is delineated. The present methylation reaction of inosine nucleotide utilizes dimethyl sulfate as a methylating agent and water as a solvent at room temperature. It is noteworthy that the present methylation reaction proceeds smoothly under aqueous conditions that is highly regioselective to afford exclusive 7-methylinosine nucleotide in good yields with high purity (>99.5%).
- Senthilvelan, Annamalai,Shanmugasundaram, Muthian,Kore, Anilkumar R.
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- Mode of action of recombinant hypoxanthine-guanine phosphoribosyltransferase from Mycobacterium tuberculosis
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Tuberculosis (TB) is the second most important cause of mortality worldwide due to a single infectious agent, Mycobacterium tuberculosis. A better understanding of the purine salvage pathway can unveil details of the biology of M. tuberculosis that might be used to develop new strategies to combat this pathogen. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is an enzyme from the purine phosphoribosyltransferase (PRTase) family and catalyzes the conversion of hypoxanthine or guanine and 5-phospho-α-d-ribose 1-diphosphate (PRPP) to, respectively, inosine 5′-monophosphate (IMP) or guanosine 5′-monophosphate (GMP), and pyrophosphate (PPi). Gel filtration chromatography has shown that recombinant M. tuberculosis HGPRT (MtHGPRT) is homodimeric. A sequential compulsory ordered enzyme mechanism with PRPP as the substrate that binds to free MtHGPRT enzyme and PPi as the first product to dissociate is proposed based on kinetic data and thermodynamics of ligand binding from isothermal titration calorimetry (ITC) results. ITC data have also provided thermodynamic signatures of non-covalent interactions for PRPP, IMP and GMP binding to free MtHGPRT. Thermodynamic activation parameters (Ea, ΔG#, ΔS#, ΔH#) for the MtHGPRT-catalyzed chemical reaction, pre-steady-state kinetics, solvent kinetic isotope effects, equilibrium constants and pH-rate profiles are also presented. Pre-steady-state analysis reveals that there is an initial rapid phase (burst) followed by a slower phase, suggesting that product release is rate limiting. The data here described provide a better understanding of the mode of action of MtHGPRT.
- Patta, Paulo C.,Martinelli, Leonardo K. B.,Rotta, Mariane,Abbadi, Bruno L.,Santos, Diogenes S.,Basso, Luiz A.
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- The role for glutamic acid at position 196 in human hypoxanthine phosphoribosyltransferase (HPRT) as investigated using site-directed mutagenesis
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The crystal structure of human HPRT reveals the involvement of E196 side chain at the A-B dimer interface. Interference by valine substitution at this position (E196V), as identified in patients with Lesch-Nyhan disease, nearly abolishes enzymatic activity. Kinetic analysis of the active mutants (E196A, E196D, E196Q, and E196R) suggests that interaction between K68 and E196 side chains contributes to stabilization of cis-configuration during the catalytic cycle. The study also provides further insight into the role of A-B dimer interactions relating to K68 in the regulation of cis-trans isomerization that potentially governs the rate-limiting steps in the HPRT reaction. Copyright Taylor & Francis Group, LLC.
- Canyuk,E-Wan,Keawwijit,Nualnoi,Sirisatean,Tansakul,Tanthana
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- Phosphorylation and dephosphorylation of polyhydroxy compounds by class A bacterial acid phosphatases
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Nonspecific acid phosphatases share a conserved active site with mammalian glucose-6-phosphatases (G6Pase). In this work we examined the kinetics of the phosphorylation of glucose and dephosphorylation of glucose-6-phosphate (G6P) catalysed by the acid phosphatases from Shigella flexneri (PhoN-Sf) and Salmonella enterica (PhoN-Se). PhoN-Sf is able to phosphorylate glucose regiospecifically to G6P, glucose-1-phosphate is not formed. The Km for glucose using pyrophosphate (PPi) as a phosphate donor is 5.3 mM at pH 6.0. This value is not significantly affected by pH in the pH region 4-6. The Km value for G6P by contrast is much lower (0.02 mM). Our experiments show these bacterial acid phosphatases form a good model for G6Pase. We also studied the phosphorylation of inosine to inosine monophosphate (IMP) using PPi as the phosphate donor. PhoN-Sf regiospecifically phosphorylates inosine to inosine-5′-monophosphate whereas PhoN-Se produces both 5′IMP and 3′IMP. The data show that during catalysis an activated phospho-enzyme intermediate is formed that is able to transfer its phosphate group to water, glucose or inosine. A general mechanism is presented of the phosphorylation and dephosphorylation reaction catalysed by the acid phosphatases. Considering the nature of the substrates that are phosphorylated it is likely that this class of enzyme is able to phosphorylate a wide range of hydroxy compounds.
- Tanaka, Naoko,Hasan, Zulfiqar,Hartog, Aloysius F.,Van Herk, Teunie,Wever, Ron
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- Phosphorylation of nucleosides with phosphorus oxychloride in trialkyl phosphate
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The reaction of guanosine and triethyl phosphate at 50°C for 15 min produced the guanosine-triethyl phosphate complex in which triethyl phosphate is coordinated to guanosine of high-anti form in a 1:1 molar ratio. During the conversion of guanosine to guanosine 5'-monophosphate with phosphorus oxychloride, the guanosine-triethyl phosphate complex showed excellent selectivity and high reactivity toward phosphorus oxychloride compared with those of guanosine. The rate of selective phosphorylation of guanosine into guanosine 5'-monophosphate was markedly improved by preheating the mixture of guanosine and triethyl phosphate at 50°C, followed by adding phosphorus oxychloride to the mixture at 0°C. Thus, the 5'-phosphorylation of guanosine with phosphorus oxychloride in triethyl phosphate is considered to progress via the guanosine-triethyl phosphate complex as the reaction intermediate.
- Ikemoto,Haze,Hatano,Kitamoto,Ishida,Nara
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- Thermophilic phosphoribosyltransferases Thermus thermophilus HB27 in nucleotide synthesis
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Phosphoribosyltransferases are the tools that allow the synthesis of nucleotide analogues using multi-enzymatic cascades. The recombinant adenine phosphoribosyltransferase (TthAPRT) and hypoxanthine phosphoribosyltransferase (TthHPRT) from Thermus thermophilus HB27 were expressed in E.coli strains and purified by chromatographic methods with yields of 10-13 mg per liter of culture. The activity dependence of TthAPRT and TthHPRT on different factors was investigated along with the substrate specificity towards different heterocyclic bases. The kinetic parameters for TthHPRT with natural substrates were determined. Two nucleotides were synthesized: 9-(β-D-ribofuranosyl)-2-chloroadenine 5'-monophosphate (2-l-AMP) using TthAPRT and 1-(β-Dribofuranosyl)pyrazolo[3,4-d]pyrimidine-4-one 5'-monophosphate (Allop-MP) using TthPRT.
- Fateev, Ilja V.,Sinitsina, Ekaterina V.,Bikanasova, Aiguzel U.,Kostromina, Maria A.,Tuzova, Elena S.,Esipova, Larisa V.,Muravyova, Tatiana I.,Kayushin, Alexei L.,Konstantinova, Irina D.,Esipov, Roman S.
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p. 3098 - 3105
(2019/01/21)
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- Identification and characterization of guanosine 5′-monophosphate reductase of Trypanosoma congolense as a drug target
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Trypanosoma congolense is one of the most prevalent pathogens which causes trypanosomosis in African animals, resulting in a significant economic loss. In its life cycle, T. congolense is incapable of synthesizing purine nucleotides via a de novo pathway, and thus relies on a salvage pathway to survive. In this study, we identified a gene from T. congolense, TcIL3000_5_1940, as a guanosine 5′-monophosphate reductase (GMPR), an enzyme that modulates the concentration of intracellular guanosine in the pathogen. The recombinant protein was expressed in Escherichia coli, and the gene product was enzymatically confirmed as a unique GMPR, designated as rTcGMPR. This enzyme was constitutively expressed in glycosomes at all of the parasite's developmental stages similar to other purine nucleotide metabolic enzymes. Mycophenolic acid (MPA) was found to inhibit rTcGMPR activity. Hence, it is a potential lead compound for the design of trypanocidal agents, specifically GMPR inhibitor.
- Sarwono, Albertus Eka Yudistira,Suganuma, Keisuke,Mitsuhashi, Shinya,Okada, Tadashi,Musinguzi, Simon Peter,Shigetomi, Kengo,Inoue, Noboru,Ubukata, Makoto
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p. 537 - 544
(2017/07/10)
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- Deamination of 6-aminodeoxyfutalosine in menaquinone biosynthesis by distantly related enzymes
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Proteins of unknown function belonging to cog1816 and cog0402 were characterized. Sav2595 from Steptomyces avermitilis MA-4680, Acel0264 from Acidothermus cellulolyticus 11B, Nis0429 from Nitratiruptor sp. SB155-2 and Dr0824 from Deinococcus radiodurans R1 were cloned, purified, and their substrate profiles determined. These enzymes were previously incorrectly annotated as adenosine deaminases or chlorohydrolases. It was shown here that these enzymes actually deaminate 6-aminodeoxyfutalosine. The deamination of 6-aminodeoxyfutalosine is part of an alternative menaquinone biosynthetic pathway that involves the formation of futalosine. 6-Aminodeoxyfutalosine is deaminated by these enzymes with catalytic efficiencies greater than 10 5 M-1 s-1, Km values of 0.9-6.0 μM, and kcat values of 1.2-8.6 s-1. Adenosine, 2′-deoxyadenosine, thiomethyladenosine, and S-adenosylhomocysteine are deaminated at least an order of magnitude slower than 6-aminodeoxyfutalosine. The crystal structure of Nis0429 was determined and the substrate, 6-aminodeoxyfutalosine, was positioned in the active site on the basis of the presence of adventitiously bound benzoic acid. In this model, Ser-145 interacts with the carboxylate moiety of the substrate. The structure of Dr0824 was also determined, but a collapsed active site pocket prevented docking of substrates. A computational model of Sav2595 was built on the basis of the crystal structure of adenosine deaminase and substrates were docked. The model predicted a conserved arginine after β-strand 1 to be partially responsible for the substrate specificity of Sav2595.
- Goble, Alissa M.,Toro, Rafael,Li, Xu,Ornelas, Argentina,Fan, Hao,Eswaramoorthy, Subramaniam,Patskovsky, Yury,Hillerich, Brandan,Seidel, Ron,Sali, Andrej,Shoichet, Brian K.,Almo, Steven C.,Swaminathan, Subramanyam,Tanner, Martin E.,Raushel, Frank M.
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p. 6525 - 6536
(2013/10/01)
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- Enzymatic production of 5′-inosinic acid by a newly synthesised acid phosphatase/phosphotransferase
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5′-Nucleotides including 5′-inosinic acid have characteristic taste and important application in various foods as flavour potentiators. The selective nucleoside acid phosphatase/phosphotransferase (AP/PTase) can catalyse the synthesis of 5′-nucleotides by transfer of phosphate groups. In this study, a 747-bp gene encoding AP/PTase from Escherichia blattae was synthesised. After expression, the recombinant AP/PTase was purified using nickel-NTA. The optimal temperature and pH of this enzyme were 30°C and 5.0, respectively. The activity was partially inhibited by metal ions such as Hg2+, Ag+ and Cu2+, but not by chelating reagents such as EDTA. The values of Km and Vmax for inosine were 40 mM and 3.5 U/mg, respectively. Using this purified enzyme, 16.83 mM of 5′-IMP was synthesised from 37 mM of inosine and the molar yield reached 45.5%. Homology modelling and docking simulation were discussed.
- Liu, Zhi-Qiang,Zhang, Ling,Sun, Li-Hui,Li, Xiao-Jun,Wan, Nan-Wei,Zheng, Yu-Guo
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experimental part
p. 948 - 956
(2012/08/14)
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- Facile solid-phase synthesis of AICAR 5-monophosphate (ZMP) and its 4-N-Alkyl derivatives
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We report herein a facile, solid-phase synthesis of 5-aminol-β-D- ribofuranosylimidazole-4-carboxamide-5'-monophosphate (ZMP), a biosynthetic precursor of purine nucleotides, as well as a small collection of its 4-N-alkyl derivatives. The very difficult, direct, chemical phosphorylation of 5-amino-lβ-D-ribofuranosylimidazole-4-carboxamide (AICAR) was circumvented by installing a suitable, fully protected, phos phate group on the 5'-position of A-l-(2,4-dinitrophenyl)inosine, connected to the solid support through the 2',3'-positions, prior to the purine degradation, which led to the 5amino-imidazole-4-ca:rboxamide moiety. A plausible reaction mechanism for the formation of the ZMP imidazole was also reported.
- Oliviero, Giorgia,D'Errico, Stefano,Borbone, Nicola,Amato, Jussara,Piccialli, Vincenzo,Piccialli, Gennaro,Luciano, Mayoi
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experimental part
p. 1517 - 1524
(2010/06/16)
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- Human N6-methyl-AMP/dAMP aminohydrolase (abacavir 5-monophosphate deaminase) is capable of metabolizing N6-substituted purine acyclic nucleoside phosphonates
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Recombinant human abacavir monophosphate deaminase (hABC-MP deaminase) was compared with the recently described rat N6-methyl-AMP (meAMP) aminohydrolase. hABC-MP deaminase, a 42 kDa polypeptide, exists predominantly as a monomer under non-denaturing conditions. Similar to the rat enzyme, hABC-MP deaminase efficiently catalyzes the hydrolytic deamination of natural substrates meAMP (5), N6,N6-dimethyl-AMP (13) and medAMP (6). Acyclic nucleoside phosphonate (ANP) N6-cyclopropyl-2,6-diamino-9-[2- (phosphonomethoxy)ethyl]purine (cPrPMEDAP) (1), an intermediate intracellular metabolite of antileukemic agent GS-9219, was effectively converted to the corresponding active guanine analog by hABC-MP deaminase. In addition to cPrPMEDAP (1), a number of other biologically active N6-substituted purine ANPs are alternative substrates for hABC-MP deaminase. The efficiency of their deamination depends on the character of N6-substitution in the adenine and/or 2,6-diaminopurine ring. ANPs with N6-cyclic substituents are deaminated more readily than corresponding compounds with aliphatic substituents of the same length. The deamination of ANPs is also influenced by modifications at the phosphonoalkyl side chain. Among 9-[2-(phosphonomethoxy)propyl] ANPs, (S)-enantiomers are preferred to (R)-enantiomers. Alternatively, the presence of extended 9-[2-(phosphonoethoxy) ethyl] moiety leads to a moderate increase in the reaction velocity compared to cPrPMEDAP (1). Comparison of hABC-MP deaminase and the rat meAMP aminohydrolase across a broad spectrum of N6-substituted substrates revealed a strong correlation of their substrate specificities. Similar to the rat meAMP aminohydrolase, hABC-MP deaminase was highly sensitive to deoxycoformycin monophosphate, but not to the guanine product of cPrPMEDAP (1) deamination. Together, these data demonstrate that hABC-MP deaminase is human meAMP aminohydrolase involved in the intracellular activation of biologically active N6-substituted nucleotide analogs.
- Schinkmanova, Marketa,Votruba, Ivan,Shibata, Riri,Han, Bin,Liu, Xiaohong,Cihlar, Tomas,Holy, Antonin
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p. 275 - 291
(2008/12/22)
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- Process for producing a mixture of inosinic acid and guanosinic acid by direct phosphorylation
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In a process for producing a mixture of inosinic acid and guanosinic acid by direct phosphorylation of the 5'-hydroxy group of inosine and guanosine, a mixture of inosine and guanosine containing at least one alkali metal salt selected from alkali metal salts of inosine and/or guanosine, is reacted with a phosphorus oxyhalide or its hydrate in a polar organic solvent.
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