890-38-0Relevant articles and documents
Effects of substitutions at the 4' and 2 positions on the bioactivity of 4'-ethynyl-2-fluoro-2'-deoxyadenosine
Kirby, Karen A.,Michailidis, Eleftherios,Fetterly, Tracy L.,Steinbach, Musetta A.,Singh, Kamalendra,Marchand, Bruno,Leslie, Maxwell D.,Hagedorn, Ariel N.,Kodama, Eiichi N.,Marquez, Victor E.,Hughes, Stephen H.,Mitsuya, Hiroaki,Parniak, Michael A.,Sarafianos, Stefan G.
, p. 6254 - 6264 (2013)
Nucleos(t)ide reverse transcriptase inhibitors (NRTIs) form the backbone of most anti-HIV therapies. We have shown that 4'-ethynyl-2-fluoro-2'- deoxyadenosine (EFdA) is a highly effective NRTI; however, the reasons for the potent antiviral activity of EFdA are not well understood. Here, we use a combination of structural, computational, and biochemical approaches to examine how substitutions in the sugar or adenine rings affect the incorporation of dA-based NRTIs like EFdA into DNA by HIV RT and their susceptibility to deamination by adenosine deaminase (ADA). Nuclear magnetic resonance (NMR) spectroscopy studies of 4'-substituted NRTIs show that ethynyl or cyano groups stabilize the sugar ring in the C-2'-exo/C-3'-endo (north) conformation. Steady-state kinetic analysis of the incorporation of 4'-substituted NRTIs by RT reveals a correlation between the north conformation of the NRTI sugar ring and efficiency of incorporation into the nascent DNA strand. Structural analysis and the kinetics of deamination by ADA demonstrate that 4'-ethynyl and cyano substitutions decrease the susceptibility of adenosinebased compounds to ADA through steric interactions at the active site. However, the major determinant for decreased susceptibility to ADA is the 2-halo substitution, which alters the pKa of N1 on the adenine base. These results provide insight into how NRTI structural attributes affect their antiviral activities through their interactions with the RT and ADA active sites. Copyright
Isolation of new photoadducts from UVA-irradiated N-nitrosoproline with 2'-deoxyadenosine and characterization of photoadducts from DNA irradiated with N-nitrosoproline
Aoyama, Shuhei,Arimoto-Kobayashi, Sakae,Asahi, Chiharu,Hatano, Tsutomu,Kimura, Sachiko,Suzuki, Toshinori
, (2020/07/03)
N-nitrosoproline (NPRO) is formed from nitrosation of proline and has been reported to be non-carcinogenic and non-mutagenic. However, earlier studies in our laboratory showed that pre-irradiated NPRO can be converted to a mutagenic form. We previously investigated the reaction of NPRO with dA or dG under UVA irradiation and identified the formation of 2-pyrrolidyl-dA adducts (P1 & P2) and 8-pyrrolidyl-dG adducts (G1 & G2) as well as four known modified nucleosides, although several peaks found in the HPLC profiles of UVA-irradiated mixtures of dA and NPRO remain unidentified. In the present study we isolated new photoproducts from irradiated mixtures of dA and NPRO and identified (R)- and (S)-8-(2-pyrrolidyl)-2′-deoxyadenosine (A1 and A2) as products by MS and NMR. We also investigated the photoadducts formed in DNA treated with NPRO under UVA irradiation, and detected A1 and/or A2 (probably both), P1, P2, G1 and/or G2, and 8-oxodG as products. Under anaerobic conditions, formation of A1 and A2 was greater than that under aerobic conditions, suggesting that photo-reactions comprising pyrrolidyl radical with dA may increase under anaerobic conditions given reduced competition with oxidative photo-reactions which may decompose pyrrolidyl-dA adducts.
Bio-catalytic synthesis of unnatural nucleosides possessing a large functional group such as a fluorescent molecule by purine nucleoside phosphorylase
Hatano, Akihiko,Wakana, Hiroyuki,Terado, Nanae,Kojima, Aoi,Nishioka, Chisato,Iizuka, Yu,Imaizumi, Takuya,Uehara, Sanae
, p. 5122 - 5129 (2019/10/05)
Unnatural nucleosides are attracting interest as potential diagnostic tools, medicines, and functional molecules. However, it is difficult to couple unnatural nucleobases to the 1′-position of ribose in high yield and with β-regioselectivity. Purine nucleoside phosphorylase (PNP, EC2.4.2.1) is a metabolic enzyme that catalyses the conversion of inosine to ribose-1α-phosphate and free hypoxanthine in phosphate buffer with 100% α-selectivity. We explored whether PNP can be used to synthesize unnatural nucleosides. PNP catalysed the reaction of thymidine as a ribose donor with purine to produce 2′-deoxynebularine (3, β form) in high conversion (80%). It also catalysed the phosphorolysis of thymidine and introduced a pyrimidine base with a halogen atom substituted at the 5-position into the 1′-position of ribose in moderate yield (52-73%), suggesting that it exhibits loose selectivity. For a bulky purine substrate [e.g., 6-(N,N-di-propylamino)], the yield was lower, but addition of a polar solvent such as dimethyl sulfoxide (DMSO) increased the yield to 74%. PNP also catalysed the reaction between thymidine and uracil possessing a large functional fluorescent group, 5-(coumarin-7-oxyhex-5-yn) uracil (C4U). Conversion to 2′-deoxy-[5-(coumarin-7-oxyhex-5-yn)] uridine (dRC4U) was drastically enhanced by DMSO addition. Docking simulations between dRC4U and E. coli PNP (PDB 3UT6) showed the uracil moiety in the active-site pocket of PNP with the fluorescent moiety at the entrance of the pocket. Thus, the bulky fluorescent moiety has little influence on the coupling reaction. In summary, we have developed an efficient method for producing unnatural nucleosides, including purine derivatives and modified uracil, using PNP.