Synthesis of Pyridine, Pyrimidine and Pyridinone <i>C</i>-Nucleoside Phosphoramidites for Probing Cytosine Function in RNA
作者:Jun Lu、Nan-Sheng Li、Selene C. Koo、Joseph A. Piccirilli
DOI:10.1021/jo9016919
日期:2009.11.6
structures of the HDV ribozyme a cytosine nucleobase resides at the active site poised to participate directly in catalysis. Defining the functional role of the nucleobase requires nucleoside analogues that perturb the functional groups in a strategic manner. Herein, we have developed efficient methods for the synthesis of five C-nucleoside phosphoramiditederivatives that, when used in combination, provide
Biochemical Detection of Cytidine Protonation within RNA
作者:Adegboyega K. Oyelere、Scott A. Strobel
DOI:10.1021/ja001918t
日期:2000.10.1
Perturbation of active site functional group pK(a)s is an important strategy employed by protein enzymes to achieve catalysis. There is increasing evidence to indicate that RNAs also utilize functional group pK(a) perturbation for folding and reactivity. one of the best candidates for a functionally relevant pK(a) perturbation is the N3 of C (pK(a) 4.2), which could be sufficiently raised to allow protonation near physiological pH. Here we report the synthesis and use of a series of alpha -phosphorothioate tagged cytidine analogues whose altered N3 pK(a)s make it possible to efficiently detect functionally relevant protonation events by nucleotide analogue interference mapping. 6-Azacytidine (n(6)C alphaS) and 5-fluorocytidine (f(5)C alphaS) both have enhanced acidity at the N3 position (pK(a) 2.6 and 2.3, respectively) but leave the hydrogen bonding face of C otherwise unaffected. In contrast, pseudoisocytidine (Psi iC alphaS) is a charge neutral analogue that mimics the hydrogen bonding character of protonated C. To test the utility of these analogues, we characterized the C300(+)-G97-C277 mutant form of the Tetrahymena group I intron, which is predicted to require C300 protonation for ribozyme folding and reactivity. At neutral to alkaline pHs, C300 was the only site of n(6)C alphaS and f(5)C alphaS interference within the intron, yet both interferences were rescued at acidic pH. Furthermore,Psi iC alphaS substitution at C300 resulted in enhanced activity at alkaline pHs, consistent with the presence of an N3 proton under the pH conditions studied. Interference mapping with these analogues provides an efficient and sensitive means to identify every site within an RNA where cytidine protonation is important for RNA function and may make it possible to identify C's that participate in general acid/base catalysis within ribozyme active sites.
Reichman,U. et al., Journal of Heterocyclic Chemistry, 1976, vol. 13, p. 933 - 935
作者:Reichman,U. et al.
DOI:——
日期:——
OLIGONUCLEOTIDE PROBES BEARING QUENCHABLE FLUORESCENT LABELS, AND METHODS OF USE THEREOF
申请人:Bayer Corporation
公开号:EP1009852A2
公开(公告)日:2000-06-21
PURIFICATION OF OLIGOMERS USING DUAL-END SELECTION