Models of DNA C1‘ Radicals. Structural, Spectral, and Chemical Properties of the Thyminylmethyl Radical and the 2‘-Deoxyuridin-1‘-yl Radical
作者:Chryssostomos Chatgilialoglu、Carla Ferreri、Rita Bazzanini、Maurizio Guerra、Seung-Yong Choi、Calvin J. Emanuel、John H. Horner、Martin Newcomb
DOI:10.1021/ja001783r
日期:2000.10.1
thyminylmethyl radical and the 2‘-deoxyuridin-1‘-ylradical were studied. The former radical was produced in laser flash photolysis (LFP) studies from two precursors derived from thyminylacetic acid, the N-hydroxypyridine-2-thione ester (PTOC ester), and the phenylselenyl ester. The thyminylmethyl radical has an absorbance in the range 315−340 nm. The rate constant for its reaction with octadecanethiol
Competitive Inhibition of Uracil DNA Glycosylase by a Modified Nucleotide Whose Triphosphate is a Substrate for DNA Polymerase
作者:Haidong Huang、James T. Stivers、Marc M. Greenberg
DOI:10.1021/ja807705z
日期:2009.2.4
Base excision repair (BER) enzymes are attractive targets for antiviral and anticancer agents. A number of nucleotides and nucleotide analogues are potent competitive inhibitors of BER glycosylases when they are incorporated into synthetic oligonucleotides. However, these molecules often are not substrates for DNA polymerases, which limits their utility in cells and as potential therapeutic agents. 1'-Cyano-2'-deoxyuridine (CNdU) is a nanomolar competitive inhibitor of uracil DNA glycosylase. In addition, the respective nucleotide triphosphate is accepted as a substrate by the Klenow fragment (exo-) of DNA polymerase I from E. coli. This is the first competitive inhibitor of UDG that is incorporated into DNA by Klenow exo-, a model replicative polymerase. 1'-Cyano-2'-deoxyuridine (CNdU) and related molecules may prove useful as a new family of therapeutic or experimental agents that target DNA repair by using the cells' polymerase(s) to incorporate them into DNA. A potential benefit of such a mechanism is that multiple incorporations can occur for longer DNA molecules leading to amplification of the inhibitory effect beyond that seen here with short DNA duplexes.
Anionically induced formation of anomeric spironucleosides from 1′-C-cyano-2′-deoxyuridine
The reaction of the 1'-C-cyano-2'-deoxyuridine derivative 1 with organolithium reagents can be favorably tuned to give a new class of anomeric spironucleosides. (C) 1999 Elsevier Science Ltd. All rights reserved.
Kinetics and Stereoselectivity of Thiol Trapping of Deoxyuridin-1‘-yl in Biopolymers and Their Relationship to the Formation of Premutagenic α-Deoxynucleotides
作者:Jae-Taeg Hwang、Marc M. Greenberg
DOI:10.1021/ja990152y
日期:1999.5.1
alpha-Deoxynucleotides are potentially deleterious lesions when produced in DNA. They are presumably formed in part via misrepair of the respective C1'-nucleotide radicals by thiols. However, the selectivity and extent to which these lesions are formed via this pathway has not been ascertained. Using the ability to independently generate deoxyuridin-1'-yl (4) at a defined site in a biopolymer, we have determined that thiol trapping in duplex DNA occurs with high stereoselectivity from the ct-face, resulting in restoration of the naturally occurring beta-deoxynucleotide. The observed stereoselectivity of thiol trapping in duplex DNA suggests that 4 is intrahelical. The rate constant for hydrogen atom donation to 4 is reduced 2-3-fold in double-stranded DNA compared to single-stranded DNA. This decrease is attributed to the relative inaccessibility of the C1'-position in duplex DNA. The combination of these two properties of 4 indicates that, at O-2 concentrations present in aerated water, alpha-deoxynucleotide formation should constitute a minor component of the reactivity of C1'-radicals. Accordingly, the chemical biology of other lesions derived from formal damage at C1'-position could be significant.
Synthesis and Biological Evaluation of 1′-<i>C</i>-Cyano-Pyrimidine Nucleosides
2'-Deoxy-, 2'-bromo-, and arabine-1'-C-cyano-pyrimidine nucleosides were synthesized from O-2,2'-cyclouridine. Incorporation of cyano group at the anomeric position was achieved by treatment of 1',2'-unsaturated uridine with NBS in the presence of pivalic acid followed by TMS-cyanide and stannic chloride. Antineoplastic and antiviral activities of those compounds are also discussed.