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Reiner T, Kvasyuk E, Pfleiderer W. Nucleotides, Part LXVI,β-Heteroarylethyl Groups - New Phosphate-Protecting Groups for Phosphotriester Chemistry. Helv Chim Acta 2000. [DOI: 10.1002/1522-2675(20001108)83:11<3053::aid-hlca3053>3.0.co;2-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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102
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Cramer H, Pfleiderer W. Nucleotides LXIV[1]: synthesis hydridization and enzymatic degradation studies of 2'-O-methyloligoribonucleotides and 2'-O-methyl/deoxy gapmers. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2000; 19:1765-77. [PMID: 11200271 DOI: 10.1080/15257770008045458] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
2'-O-Methyloligoribonucleotides, deoxyoligonucleotides and 2'-O-methyl/deoxy gapmers were synthesized using solid phase phosphoramidite chemistry employing the 2-(4-nitrophenyl)ethyl (npe) protection strategy. Melting temperatures of the synthesized oligonucleotides as well as their stability against degradation by several different nucleases were determined. 2'-O-Methyloligoribonucleotides showed the highest melting temperatures (Tm's) whereas 2'-O-methyl/deoxy gapmers revealed either slightly higher or surprizingly no thermal stabilities compared with their deoxy analogs when using self-complementary sequences. Gapmers with four 2'-O-methyl nucleotides on both ends showed about the same stability as all 2'-O-methyloligoribonucleotides against micrococal nuclease, nuclease S1, and snake venom phosphodiesterase.
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Wagner T, Pfleiderer W. Nucleotides, Part LXV, Synthesis of 2′-Deoxyribonucleoside 5′-Phosphoramidites: New Building Blocks for the Inverse (5′-3′)-Oligonucleotide Approach. Helv Chim Acta 2000. [DOI: 10.1002/1522-2675(20000809)83:8<2023::aid-hlca2023>3.0.co;2-p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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105
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Oettl K, Pfleiderer W, Reibnegger G. Formation of Oxygen Radicals in Solutions of Different 7,8-Dihydropterins: Quantitative Structure-Activity Relationships. Helv Chim Acta 2000. [DOI: 10.1002/(sici)1522-2675(20000510)83:5<954::aid-hlca954>3.0.co;2-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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106
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Kotsonis P, Fröhlich LG, Shutenko ZV, Horejsi R, Pfleiderer W, Schmidt HH. Allosteric regulation of neuronal nitric oxide synthase by tetrahydrobiopterin and suppression of auto-damaging superoxide. Biochem J 2000; 346 Pt 3:767-76. [PMID: 10698705 PMCID: PMC1220911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The underlying mechanisms regulating the activity of the family of homodimeric nitric oxide synthases (NOSs) and, in particular, the requirement for (6R)-5,6,7,8-tetrahydro-L-biopterin (H(4)Bip) are not fully understood. Here we have investigated possible allosteric and stabilizing effects of H(4)Bip on neuronal NOS (NOS-I) during the conversion of substrate, L-arginine, into L-citrulline and nitric oxide. Indeed, in kinetic studies dual allosteric interactions between L-arginine and H(4)Bip activated recombinant human NOS-I to increase L-arginine turnover. Consistent with this was the observation that H(4)Bip, but not the pterin-based NOS inhibitor 2-amino-4,6-dioxo-3,4,5,6,8,8a,9,10-octahydrooxazolo[1, 2-f]-pteridine (PHS-32), caused an L-arginine-dependent increase in the haem Soret band, indicating an increase in substrate binding to recombinant human NOS-I. Conversely, L-arginine was observed to increase in a concentration-dependent manner H(4)Bip binding to pig brain NOS-I. Secondly, we investigated the stabilization of NOS quaternary structure by H(4)Bip in relation to uncoupled catalysis. Under catalytic assay conditions and in the absence of H(4)Bip, dimeric recombinant human NOS-I dissociated into inactive monomers. Monomerization was related to the uncoupling of reductive oxygen activation, because it was inhibited by both superoxide dismutase and the inhibitor N(omega)-nitro-L-arginine. Importantly, H(4)Bip was found to react chemically with superoxide (O(2)(-.)) and enzyme-bound H(4)Bip was consumed under O(2)(-.)-generating conditions in the absence of substrate. These results suggest that H(4)Bip allosterically activates NOS-I and stabilizes quaternary structure by a novel mechanism involving the direct interception of auto-damaging O(2)(-.).
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107
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Lang H, Gottlieb M, Schwarz M, Farkas S, Schulz B, Himmelsbach F, Charubala R, Pfleiderer W. Nucleotides, Part LXIII, New 2-(4-Nitrophenyl)ethyl(Npe)- and 2-(4-Nitrophenyl)ethoxycarbonyl(Npeoc)-Protected 2′-Deoxyribonucleosides and Their 3′-Phosphoramidites - Versatile Building Blocks for Oligonucleotide Synthesis. Helv Chim Acta 1999. [DOI: 10.1002/(sici)1522-2675(19991215)82:12<2172::aid-hlca2172>3.0.co;2-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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108
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Fröhlich LG, Kotsonis P, Traub H, Taghavi-Moghadam S, Al-Masoudi N, Hofmann H, Strobel H, Matter H, Pfleiderer W, Schmidt HH. Inhibition of neuronal nitric oxide synthase by 4-amino pteridine derivatives: structure-activity relationship of antagonists of (6R)-5,6,7,8-tetrahydrobiopterin cofactor. J Med Chem 1999; 42:4108-21. [PMID: 10514281 DOI: 10.1021/jm981129a] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The family of nitric oxide synthases (NOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO), an important cellular messenger molecule which has been implicated in the pathophysiology of septic shock and inflammatory and neurodegenerative disease states. NOS can be maximally activated by the ubiquitous cofactor, (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip), and antagonists of H(4)Bip may be of therapeutic importance to inhibit pathologically high NO formation. The 4-amino substituted analogue of H(4)Bip was reported to be a potent NOS inhibitor. Therefore, we developed a series of novel 4-amino pteridine derivatives, anti-pterins, to pharmacologically target the neuronal isoform of nitric oxide synthase (NOS-I). To functionally characterize the pterin/anti-pterin interaction and establish a structure-activity relationship (SAR), we systematically altered the substituents in the 2-, 4-, 5-, 6-, and 7-position of the pteridine nucleus. Varying the substitution pattern in the 2-, 5-, and 7-position resulted in no significant inhibitory effect on enzyme activity. In contrast, bulky substituents in the 6-position, such as phenyl, markedly increased the inhibitory potency of the reduced 4-amino-5,6,7,8-tetrahydropteridines, possibly as a consequence of hydrophobic interactions within NOS-I. However, this was not the case for the aromatic 4-amino pteridines. Interestingly, chemical modification of the 4-amino substituent by dialkyl/diaralkylation together with 6-arylation of the aromatic 2,4-diamino pteridine resulted in potent and efficacious inhibitors of NOS-I, suggesting possible hydrophilic and hydrophobic interactions within NOS-I. This SAR agrees with (a) the recently published crystal structure of the oxygenase domain of the inducible NOS isoform (NOS-II) and (b) the comparative molecular field analysis of selected NOS-I inhibitors, which resulted in a 3D-QSAR model of the pterin binding site interactions. Further optimization should be possible when the full length structure of NOS-I becomes available.
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Reif A, Fröhlich LG, Kotsonis P, Frey A, Bömmel HM, Wink DA, Pfleiderer W, Schmidt HH. Tetrahydrobiopterin inhibits monomerization and is consumed during catalysis in neuronal NO synthase. J Biol Chem 1999; 274:24921-9. [PMID: 10455167 DOI: 10.1074/jbc.274.35.24921] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biosynthesis of nitric oxide (NO) is catalyzed by homodimeric NO synthases (NOS). For unknown reasons, all NOS co-purify with substoichiometric amounts of (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip) and require additional H(4)Bip for maximal activity. We examined the effects of H(4)Bip and pterin-derived inhibitors (anti-pterins) on purified neuronal NOS-I quaternary structure and H(4)Bip content. During L-arginine turnover, NOS-I dimers time dependently dissociated into inactive monomers, paralleled by a loss of enzyme-associated pterin. Dimer dissociation was inhibited when saturating levels of H(4)Bip were added during catalysis. Similar results were obtained with pterin-free NOS-I expressed in Escherichia coli. This stabilizing effect of H(4)Bip was mimicked by the anti-pterin 2-amino-4,6-dioxo-3,4,5,6,8,8a,9, 10-octahydro-oxazolo[1,2f]-pteridine (PHS-32), which also displaced NOS-associated H(4)Bip in a competitive manner. Surprisingly, H(4)Bip not only dissociated from NOS during catalysis, but was only partially recovered in the solute (50.0 +/- 16.5% of control at 20 min). NOS-associated H(4)Bip appeared to react with a NOS catalysis product to a derivative distinct from dihydrobiopterin or biopterin. Under identical conditions, reagent H(4)Bip was chemically stable and fully recovered (95.5 +/- 3.4% of control). A similar loss of both reagent and enzyme-bound H(4)Bip and dimer content was observed by NO generated from spermine NONOate. In conclusion, we propose a role for H(4)Bip as a dimer-stabilizing factor of neuronal NOS during catalysis, possibly by interfering with enzyme destabilizing products.
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Kvasyuk EI, Mikhailopulo IA, Suhadolnik RJ, Henderson EE, Muto NF, Iacono KT, Homon J, Pfleiderer W. Synthesis and biological activity of 2',5'-oligoadenylate trimers containing 5'-terminal 5'-amino-5'-deoxy- and 5'-amino-3',5'-dideoxyadenosine derivatives. NUCLEOSIDES & NUCLEOTIDES 1999; 18:1483-4. [PMID: 10474228 DOI: 10.1080/07328319908044760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Some new 2',5'-oligonucleotide trimers containing 5'-terminal 5'-amino-5'-deoxy- and 5'-amino-3',5'-dideoxyadenosine derivatives have been synthesized. Some of the trimers showed biological inhibitions of HIV-1 reverse transcriptase (RT), HIV-1 induced syncytia formation and PCR amplification.
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112
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Schirmeister-Tichy H, Alvarado GG, Pfleiderer W. The 9-fluorenylmethoxycarbonyl (Fmoc) group and its use in oligonucleotide synthesis. NUCLEOSIDES & NUCLEOTIDES 1999; 18:1219-20. [PMID: 10474216 DOI: 10.1080/07328319908044667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The introduction of the base-labile 9-fluorenylmethoxycarbonyl (Fmoc) group into the exocyclic amino function of 2'-deoxynucleosides and their dimethoxytritylation and phosphitylation is described. The resulting key intermediates were investigated in the built-up of different oligodeoxyribonucleoside phosphate and thiophosphate chains which were deprotected under mild basic conditions leading to crude oligomers of high purity.
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Schirmeister-Tichy H, Iacono K, Muto N, Homan J, Suhadolnik R, Pfleiderer W. Nucleotides, Part LIX, Synthesis, Characterization, and Biological Activities of New Potential Antiviral Agents: (2′ - 5′)Adenylate Trimer Analogs Containing 3′-Deoxy-3′-(hexadecanoylamino)adenosine at the 2′-Terminus. Helv Chim Acta 1999. [DOI: 10.1002/(sici)1522-2675(19990407)82:4<597::aid-hlca597>3.0.co;2-v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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115
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Cramer H, Pfleiderer W. Nucleotides, Part LX, Synthesis and Characterization of New 2′-O-Methylriboside 3′-O-Phosphoramidites Useful for the Solid-Phase Synthesis of 2′-O-Methyloligoribonucleotides. Helv Chim Acta 1999. [DOI: 10.1002/(sici)1522-2675(19990407)82:4<614::aid-hlca614>3.0.co;2-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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116
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Lee HW, Oh CH, Geyer A, Pfleiderer W, Park YS. Characterization of a novel unconjugated pteridine glycoside, cyanopterin, in Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1410:61-70. [PMID: 10076015 DOI: 10.1016/s0005-2728(98)00175-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A new pteridine glycoside, called cyanopterin, was isolated from Synechocystis sp. PCC 6803 and its structure was elucidated as 6-[1-(4-O-methyl-(alpha-d-glucuronyl)-(1, 6)-(beta-d-galactosyloxy]methylpterin by chemical degradation and 1H- and 13C-NMR spectroscopic means. Cyanopterin is constitutively synthesized at a relatively high intracellular concentration that is comparable to that of chlorophyll a in a molar ratio of approximately 1 to 1.6. The in vivo oxidation state of cyanopterin is primarily the fully reduced 5,6,7,8-tetrahydro form. The cellular function is unknown at present. The findings have established a model system, using Synechocystis sp. PCC 6803, for studies of the physiological functions of unconjugated pteridine glycosides found mostly in cyanobacteria.
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Bömmel HM, Reif A, Fröhlich LG, Frey A, Hofmann H, Marecak DM, Groehn V, Kotsonis P, La M, Köster S, Meinecke M, Bernhardt M, Weeger M, Ghisla S, Prestwich GD, Pfleiderer W, Schmidt HH. Anti-pterins as tools to characterize the function of tetrahydrobiopterin in NO synthase. J Biol Chem 1998; 273:33142-9. [PMID: 9837881 DOI: 10.1074/jbc.273.50.33142] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric oxide synthases (NOS) are homodimeric enzymes that NADPH-dependently convert L-arginine to nitric oxide and L-citrulline. Interestingly, all NOS also require (6R)-5,6,7, 8-tetrahydro-L-biopterin (H4Bip) for maximal activity although the mechanism is not fully understood. Basal NOS activity, i.e. that in the absence of exogenous H4Bip, has been attributed to enzyme-associated H4Bip. To elucidate further H4Bip function in purified NOS, we developed two types of pterin-based NOS inhibitors, termed anti-pterins. In contrast to type II anti-pterins, type I anti-pterins specifically displaced enzyme-associated H4Bip and inhibited H4Bip-stimulated NOS activity in a fully competitive manner but, surprisingly, had no effect on basal NOS activity. Moreover, for a number of different NOS preparations basal activity (percent of Vmax) was frequently higher than the percentage of pterin saturation and was not affected by preincubation of enzyme with H4Bip. Thus, basal NOS activity appeared to be independent of enzyme-associated H4Bip. The lack of intrinsic 4a-pterincarbinolamine dehydratase activity argued against classical H4Bip redox cycling in NOS. Rather, H4Bip was required for both maximal activity and stability of NOS by binding to the oxygenase/dimerization domain and preventing monomerization and inactivation during L-arginine turnover. Since anti-pterins were also effective in intact cells, they may become useful in modulating states of pathologically high nitric oxide formation.
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Abstract
Summary A simple direct method for the synthesis of lumazine-6,7-diamines (9, 25-27) from uracil-5,6-diamines (10-13) and methyl cyanoformimidate (24) was found. Various nucleophilic displacement reactions were performed with 7-chloro-1,3-dimethyllumazine-6-amine (17) leading to new 6,7-disubstituted 1,3- dimethyllumazine derivatives (18-23).
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119
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Blair J, Fuchs D, Pfleiderer W, Reibnegger G, Wachter H. Abstracts. Seventeenth International Winter-Workshop on Biochemical and Clinical Aspects of Pteridines. Pteridines 1998. [DOI: 10.1515/pteridines.1998.9.3.145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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120
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Martínez A, Vageli O, Pfleiderer W, Flatmark T. Proton NMR Studies on the Conformation of the Pterin Cofactor Bound at the Active Site of Recombinant Human Tyrosine Hydroxylase. Pteridines 1998. [DOI: 10.1515/pteridines.1998.9.1.44] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
SummaryThe binding of L-erythro-7,S-dihydrobiopterin (BH2) in the presence of L-Phe to recombinant human tyrosine hydroxylase was studied by 1H-NMR spectroscopy. The distances (± 1.3 A) from the active site metal were estimated to be 5 .3-6.4 A for observable protons of BH2 and 7 .0-7.9 A for L-Phe protons. Due to the lack of constraints from the pyrimidine ring in BH2 , two families of conformers were computed, with an average distance from the C4a in the pterin ring to the iron of 3.7 A (family A) and S.S A (family B). The conformers for 6-methyl-tetrahydropterin bound to the enzyme at near anaerobic conditions in the absence of L-Phe were also grouped into two families, with C4a-metal distances of 3.0-4.0 A (A) and 7.0-7.5 A (B). Based on the estimated conformation of the enzyme bound 5,6,7,S-tetrahydro- 3-methylpterin, family A of conformers was selected for both oxidized and reduced pterins. Our results indicate that the pterin does not coordinate to the iron, which seems to be involved both in the binding and activation of O2 and in the C-O bond formation in the aromatic ring of the substrate.
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121
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Waldvogel SR, Pfleiderer W. Nucleotides. Part LV. Synthesis and application of a novel linker for solid-phase synthesis of modified oligonucleotides. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810106] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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122
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Greiner B, Pfleiderer W. Nucleotides. Part LVII.. Synthesis of phosphoramidite building blocks of 2?-amino-2?-deoxyribonucleosides: New compounds for oligonucleotide synthesis. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810556] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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123
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Melguizo M, Gottlieb M, Charubala R, Pfleiderer W. Nucleosides. LXII. Synthesis of 6-Methyl-8-(2-deoxy-β-D-ribofuranosyl)-isoxanthopterin and Derivatives. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 1998. [DOI: 10.1080/07328319808005168] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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124
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Matysiak S, Fitznar HP, Schnell R, Pfleiderer W. Nucleosides. Part LXIII. Acetals as new 2?-O-protecting functions for the synthesis of oligoribonucleotides: Synthesis of uridine building blocks and evaluation of their relative acid stability. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810557] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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125
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Kvasyuk EI, Kulak TI, Tkachenko OV, Sentyureva SL, Mikhailopulo IA, Suhadolnik RJ, Henderson EE, Horvath SE, Guan MX, Pfleiderer W. Nucleotides. Part LVI. Synthesis and biological activity of modified (2?-5?)triadenylates containing 2?-terminal 2?,3?-dideoxy-3?-fluoroadenosine derivatives. Helv Chim Acta 1998. [DOI: 10.1002/hlca.19980810538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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