- Production, characterization and synthetic application of a purine nucleoside phosphorylase from Aeromonas hydrophila
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Purine nucleoside phosphorylase (PNP) from Aeromonas hydrophila encoded by the deoD gene has been over-expressed in Escherichia coli, purified, characterized about its substrate specificity and used for the preparative synthesis of some 6-substituted purine-9-ribosides. Substrate specificity towards natural nucleosides showed that this PNP catalyzes the phosphorolysis of both 6-oxo- and 6-aminopurine (deoxy)ribonucleosides. A library of nucleoside analogues was synthesized and then submitted to enzymatic phosphorolysis as well. This assay revealed that 1-, 2-, 6- and 7-modified nucleosides are accepted as substrates, whereas 8-substituted nucleosides are not. A few transglycosylation reactions were carried out using 7-methylguanosine iodide (4) as a d-ribose donor and 6-substituted purines as acceptor. In particular, following this approach, 2- amino-6-chloropurine-9-riboside (2c), 6-methoxypurine- 9-riboside (2d) and 2-amino-6-(methylthio)purine- 9-riboside (2g) were synthesized in very high yield and purity.
- Ubiali, Daniela,Serra, Carla D.,Serra, Immacolata,Morelli, Carlo F.,Terreni, Marco,Albertini, Alessandra M.,Manitto, Paolo,Speranzab, Giovanna
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experimental part
p. 96 - 104
(2012/04/11)
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- High-throughput five minute microwave accelerated glycosylation approach to the synthesis of nucleoside libraries
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The Vorbrueggen glycosylation reaction was adapted into a one-step 5 min/130 °C microwave assisted reaction. Triethanolamine in acetontrile containing 2% water was determined to be optimal for the neutralization of trimethylsilyl inflate allowing for direct MPLC purification of the reaction mixture. When coupled with a NH3/methanol deprotection reaction, a high-throughput method of nucleoside library synthesis was enabled. The method was demonstrated by examining the ribosylation of 48 nitrogen containing heteroaromatic bases that included 25 purines, four pyrazolopyrimidines, two 8-azapurines, one 2-azapurine, two imidazopyridines, two benzimidazoles, three imidazoles, three 1,2,4-triazoles, two pyrimidines, two 3-deazapyrimidines, one quinazolinedione, and one alloxazine. Of these, 32 yielded single regioisomer products, and six resulted in separable mixtures. Seven examples provided inseparable regioisomer mixtures of -two to three compounds (16 nucleosides), and three examples failed to yield isolable products. For the 45 single isomers isolated, the average two-step overall yield ± SD was 26 ± 16%, and the average purity ± SD was 95 ± 6%. A total of 58 different nucleosides were prepared of which 15 had not previously been accessed directly from glycosylation/deprotection of a readily available base.
- Bookser, Brett C.,Raffaele, Nicholas B.
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p. 173 - 179
(2007/10/03)
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