Studies on N4-(2-Deoxy-D-pentofuranosyl)-4,6-diamino-5-formamidopyrimidine (FapydA) and N6-(2-De
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- 作者：Marc M. Greenberg ; Zsolt Hantosi ; Carissa J. Wiederholt ; and Christopher D. Rithner
- 刊名：Biochemistry
- 出版年：2001
- 出版时间：December 25, 2001
- 年：2001
- 卷：40
- 期：51
- 页码：15856 - 15861
- 全文大小：85K
- 年卷期：v.40,no.51(December 25, 2001)
- ISSN：1520-4995
文摘
Exposure of DNA to oxidative stress produces a variety of DNA lesions including theformamidopyrimidines, which are derived from the purines. These lesions may play important roles incarcinogenesis. We achieved the first chemical syntheses of a monomeric form of Fapy
dA (1) andoligonucleotides containing this lesion or FapydG at a defined site. Monomeric FapydA readily epimerizedat 25 
deg.gif">C in phosphate buffer (pH 7.5). The 
ddle">-anomer was favored by a ratio of 1.33:1.0, and equilibrationwas achieved in less than 7 h. Deglycosylation of FapydA in the monomer follows first-order kineticsfrom 37 to 90 deg.gif">C. The rate constants for deglycosylation of FapydA in the monomeric and oligonucleotidesubstrates were measured at a common temperature (55 deg.gif">C) and found to be the same within experimentalerror (t1/2 = 20.5 h). Implementation of the activation parameters measured for the deglycosylation of 1indicates that the half-life for deglycosylation of FapydA at 37 deg.gif">C is approximately 103 h. Analysis ofthe rate constant for deglycosylation of FapydG in an oligonucleotide, revealed that this lesion is ~25times more resistant to hydrolysis than FapydA at 55 deg.gif">C. These results indicate that FapydA and FapydGwill be sufficiently long-lived in DNA so as to warrant investigation of their genotoxicity, and both anomerswill be present during this time.
dA (1) andoligonucleotides containing this lesion or FapydG at a defined site. Monomeric FapydA readily epimerizedat 25 deg.gif">C in phosphate buffer (pH 7.5). The ddle">-anomer was favored by a ratio of 1.33:1.0, and equilibrationwas achieved in less than 7 h. Deglycosylation of FapydA in the monomer follows first-order kineticsfrom 37 to 90 deg.gif">C. The rate constants for deglycosylation of FapydA in the monomeric and oligonucleotidesubstrates were measured at a common temperature (55 deg.gif">C) and found to be the same within experimentalerror (t1/2 = 20.5 h). Implementation of the activation parameters measured for the deglycosylation of 1indicates that the half-life for deglycosylation of FapydA at 37 deg.gif">C is approximately 103 h. Analysis ofthe rate constant for deglycosylation of FapydG in an oligonucleotide, revealed that this lesion is ~25times more resistant to hydrolysis than FapydA at 55 deg.gif">C. These results indicate that FapydA and FapydGwill be sufficiently long-lived in DNA so as to warrant investigation of their genotoxicity, and both anomerswill be present during this time.