- Zn2+ -promoted hydrolysis of 3',5'-dinucleoside monophosphates and polyribonucleotides. The effect of nearest neighbours on the cleavage of phosphodiester bonds
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Pseudo first-order rate constants for the Zn2+ -promoted cleavage of 15 different dinucleoside monophosphates, 4 different ribo homopolymers and RNA III from baker's yeast have been determined. Furthermore, the distribution of various nucleosides at the 3'- and 5'-terminus of the oligomeric hydrolysis products of RNA has been quantified. On these bases, the effect of nearest neighbours on the metal-ion-promoted hydrolysis of the internucleosidic phosphodiester bonds of RNA is discussed.
- Kuusela, Satu,Loennberg, Harri
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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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- Synthesis of adenylyl-(3'----5')-guanosine and some analogues as probes to explore the molecular mechanism of stimulation of influenza virus RNA polymerase.
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Influenza virus mRNA synthesis is primed by a capped oligonucleotide which is cleaved off from a cellular mRNA by a viral protein. The dinucleotide A3'p5'G can be used as a primer for the viral RNA polymerase mediated RNA synthesis in a cell-free system. Analogues of A3'p5'G have therefore been synthesized using the phosphotriester approach, and their priming ability for the influenza virus mRNA synthesis has been determined. An absence of the 2'-hydroxyl function in the guanosine residue in the dinucleotide, as in A3'p5'dG, drastically decreased its priming ability. Similarly, an alteration of the 3'----5' phosphate linkage to a 2'----5' phosphodiester linkage affected the priming ability quite severely. However a dinucleotide, with the 2'-hydroxyl function omitted in the adenosine moiety, as in dA3'p5'G, could still stimulate the mRNA synthesis. None of the modified dinucleotides inhibited A3'p5'G or globin mRNA primed influenza mRNA synthesis.
- Heikkil?,Stridh,Oberg,Chattopadhyaya
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p. 657 - 669
(2007/10/02)
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