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981.
Abstract The base pairing ambiguity of 7-deaza-2′-deoxyinosine (c7Id, 2) was studied and was found to be the same as that of 2′-deoxyinosine. The duplex stability decreases in the order [d(c7I-C) > d(c7I-A) > d(c7I-T) > d(c7I-G)]. Modified nucleosides were used to probe the various base pair motifs which were the same for dl and c7Id. The 7-deazapurine nucleoside (2) is extremely stable against acid or base. As oligonucleotides can be prepared using phosphoramidite chemistry and DNA is accessible by enzymic polymerisation of the triphosphate of 2, the latter can be used as an universal nucleoside for the sequencing of DNA by chemical degradation and is otherwise a facile substitute of 2′-deoxyinosine when stability in acidic or alkaline solution is required. 相似文献
982.
Frank Seela Changfu Wei Alexander Melenewski Yang He Rita Kröschel Elisabeth Feiling 《Nucleosides, nucleotides & nucleic acids》2013,32(6-7):1543-1548
Abstract Parallel-stranded (ps) oligonucleotide duplexes containing several new base pairs formed between 7-deazaisoguanine and cytosine, 8-aza-7-deaza-isoguanine and cytosine, and 5-aza-7-deaza guanine and guanine are described. The stability of the pshybrids increased if the duplex contains 8-aza-7-deazaisoguanine instead of isoguanine and is decreased by 7-deazaisoguanine incorporation. The purine-purine base pair between 5-aza-7-deazaguanine and guanine was found to be more stable than that of 5-methylisocytosine with guanine. 相似文献
983.
Abstract The synthesis of phosphoramidites (2 and 3) derived from hypoxanthine and isoguanine N7-21-deoxyribonucleosides is described. Solid-phase synthesis furnishes oligonucleotides containing N7-glycosylated purines. New base pairs between purine N7- and N9-nucleosides are proposed. 相似文献
984.
Abstract Three new appropriately protected phosphoramidites have been synthesized. Two of them (1 and 2) are isosteric to that of inosine (3) [1], one is a derivative of 1′3-propanediol (4). Whereas the inosine isosteres contain an ambiguous base recognizing adenine, guanine as well as cytosine residues in double stranded DNA-fragments the 1,3-propanediol unit can be seen as a simple nucleoside substitute in a DNA chain. It contains only those structural elements necessary to form the sugar/phosphate backbone, without supplying the DNA with either a base [21 or a 2′-deoxyribofuranosyl moiety. 相似文献
985.
Muthiah Manoharan Kathleen L. Tivel Laura K. Andrade V. Mohan Thomas P. Condon C. Frank Bennett 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):969-973
Abstract Cholic acid, cholesterol, several polyamines and polyethylene glycols were conjugated to antisense oligonucleotides targeted to human or murine intercellular adhesion molecule-1 (ICAM-1) mRNA to study their effects on cellular absorption. 相似文献
986.
Natalya Ramzaeva Helmut Rosemeyer Frank Seela 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):947-950
Abstract The rate and velocity of the photoconversion of 2-chloro-2′-deoxyadenosine into 2′-deoxyisoguanosine within oligonucleotides was found to be sequence-specific and depends on the nearest neighbor. 相似文献
987.
Terence J. Walton Dipankar Ghosh Russell P. Newton A. Gareth Brenton Frank M. Harris 《Nucleosides, nucleotides & nucleic acids》2013,32(7):967-983
Abstract The use of positive ion fast atom bombardment mass-analysed ion kinetic energy (FAB/MIKE) spectroscopy to differentiate the 2′, 3′-and 5′-monophosphate isomers of adenosine, guanosine and cytidine is described. 相似文献
988.
Frank. Seela Changfu. Wei Alexander. Melenewski Elisabeth. Feiling 《Nucleosides, nucleotides & nucleic acids》2013,32(9-11):2045-2052
Abstract Parallel-stranded (ps) oligonucleotide duplexes are described containing isoguanine-cytosine and/or 5-methylisocytosine-guanine base pairs. A parallel hybrid is also formed when 5-aza-7-deazaguanine base pairs with guanine while the base pair with isoguanine results in an antiparallel duplex. Oligomers such as d(T4isoG4T4) form selfassembled tetraplexes which show a cation selectivity different from that of the G-quartet. 相似文献
989.
Abstract Phosphorylation of 1-(2-deoxy-β-D-xylofuranosyl)thymine (1) or 9-(2-deoxy-β-D-xylofuranosyl)adenine (3) with phosphoryl chloride gives the cyclic 3′,5′-phosphates (2 and 4a) but not the 5′-monophosphates 8a or 8b. The latter are obtained by phosphorylation of the 3′-0-benzoylated 2′-deoxy-β-D-xylonucleosides (7a, b) and subsequent base-catalyzed removal of the benzoyl groups. Compound 3, as the parent dA, depurinates in acidic medium, a reaction which is facilitated in the case of the N6-benzoyl derivative 9b and reduced after the introduction of an amidine protecting group. N-Glycosylic bond hydrolysis of 2′-deoxy-β-D-xylofuranosyl nucleosides is enhanced by a factor of two compared to 2′-deoxy-β-D-ribofuranosyl nucleosides. 相似文献
990.
George L. Trainor Frank W. Hobbs Anthony J. Cocuzza Pat N. Confalone 《Nucleosides, nucleotides & nucleic acids》2013,32(5-6):1175-1176
Abstract A general route for the synthesis of alkynylamino nucleoside triphosphates is described. These nucleosides can be selectively coupled through the alkynylamino group to a variety of reporter groups and used to enzymatically label DNA. 相似文献