108929-11-9Relevant articles and documents
Addition of deoxyribose to guanine and modified DNA bases by Lactobacillus helveticus trans-N-deoxyribosylase
Mueller, Michael,Hutchinson, Linda K.,Peter Guengerich
, p. 1140 - 1144 (1996)
The use of bacterial trans-N-deoxyribosylase was evaluated as an alternative method for deoxyribosylation in the synthesis of deoxyribonucleosides containing potentially mutagenic adducts. A crude enzyme preparation was isolated from Lactobacillus helveticus and compared to Escherichia coli purine nucleoside phosphorylase. trans-N-deoxyribosylase was more regioselective than purine nucleoside phosphorylase in the deoxyribosylation of Gua at the N9 atom, as compared to N7, as demonstrated by NMR analysis of the product. 5,6,7,9-Tetrahydro-7-acetoxy-9- oxoimidazo[1,2-a]purine was efficiently deoxyribosylated by trans-N- deoxyribosylase but not at all by purine nucleoside phosphorylase. Other substrates for trans-N-deoxyribosylase were N2-(2-oxoethyl)Gua, pyrimido[1,2-a]purin-10(3H)-one, 1,N2-ε-Gua, N2,3ε-Gua, 3,N4-(-Cyt, 1,N6-ε-Ade, C8-methylGua, and C8-aminoGua, most of which gave the desired isomer (bond at the nitrogen corresponding to N9 in Gua) in good yield. Neither N7-alkylpurines nor C8-(arylamino)-substituted guanines were substrates. The approach offers a relatively convenient method of enzymatic preparation of many carcinogen-DNA adducts at the nucleoside level, for either use as standards or incorporation into oligonucleotides. trans-N- deoxyribosylase can also be used to remove deoxyribose from modified deoxyribonucleosides in the presence of excess Cyt.
trans,trans-2,4-Decadienal-induced 1,N2-etheno-2'-deoxyguanosine adduct formation
Loureiro, Ana Paula M.,Di Mascio, Paolo,Gomes, Osmar F.,Medeiros, Marisa H. G.
, p. 601 - 609 (2000)
A number of ring-extended DNA adducts resulting from the reaction of α,β-unsaturated aldehydes, or their epoxides, with DNA bases have been characterized in recent years. These adducts may lead to miscoding during DNA replication, resulting, if not repaired, in mutations that can contribute to cancer development, trans,trans-2,4-Decadienal (DDE) is one of the highly cytotoxic aldehydes endogenously formed from lipid peroxidation. To evaluate its DNA damaging potential, we have investigated the reaction of DDE with 2'- deoxyguanosine (dGuo) in the presence of peroxides. Three stable adducts were isolated by reverse-phase HPLC. Adduct A1, 3-(2-deoxy-β-D-erythro- pentafuranosyl)-5,9-dihydro-9H-imidazo[2,1-i]purin-9-hydroxy, is a tautomer of 1,N2-etheno-2'-deoxyguanosine, a well-known reaction product of epoxy aldehydes with dGuo. Two new diasteroisomeric products, A2-1 and A2-2, 1- {[3-(2'-deoxy-β-D-erythropentafuranosyl)-5,9-dihydro-9H-imidazo[2,1- i]purin-9-hydroxy]-7-yl}-2-one-3 octanol, were isolated and characterized on the basis of their spectroscopic features as 1,N2-etheno adducts possessing a carbon side chain with a carbonyl and a hydroxyl group. The proposed reaction mechanism for the formation of adducts A2 involves DDE double epoxidation and hydrolysis of the C4 epoxy group prior to nucleophilic addition of the exocyclic amino group of dGuo to C1 of the aldehyde, followed by cyclization via nucleophilic attack on the C2 epoxy group by N-1 and elimination of H2O. After treatment of calf thymus DNA with DDE, formation of adducts A1 and A2 was detected by the LC/ESI/MS-MS technique. These results can contribute to a better understanding of the chemical structures of adducts resulting from the reaction of aldehydes with nucleic acid bases, a necessary step in assessing the genotoxic risks associated with this class of compounds.
In vitro synthesis of 1,N6-etheno-2′-deoxyadenosine and 1,N2-etheno-2′-deoxyguanosine by 2,4-dinitrophenol and 1,3-dinitropyrene in presence of a bacterial nitroreductase
Chiron, Serge,Barbati, Stephane,De Meo, Michel,Botta, Alain
, p. 222 - 227 (2007/10/03)
The formation of covalent nitro-PAH DNA adducts and nitro-PAH mediated oxidative lesions are two possible mechanisms for the initiation of nitro-PAH carcinogenesis. Sixty-minute incubation of 1,3-dinitropyrene (100 μM) or 1,4-dinitrophenol (100 μM) with a mixture of 150 μM NADH, 0.5 units of E. coli nitroreductase, 100 μM linoleic acid, 0.5 mM ferrous iron, and 100 μM 2′-deoxyadenosine (2′-dA) or 100 μM 2′-deoxyguanosine (2′-dG) were analyzed by liquid chromatography multistage mass spectrometry. Mixtures of 1,N6-etheno-2′-deoxyadenosine (εdA) plus 4-oxo-2-nonenal (4-ONE) and 1,N2-etheno-2′- deoxyguanosine (εdG) plus 4-ONE could be detected from 2′-dA and 2′-dG, respectively. Addition of 2% propanol inhibited the formation of etheno adducts. Analyses of disappearance kinetics of dA and dG showed that dG was more rapidly eliminated than does dA (t[1/2] = 23.3 min and 98.3 min for dG and dA, respectively). Curves of formation kinetics revealed that the peak of εdG was at 55.6 min while that of εdA was at 186.9 min. These peaks represented 1.43% and 1.25% of the original dG and dA, respectively. In both cases, the peaks were followed by rapid degradations of etheno adducts. The results, obtained in this system, do not allow any extrapolation to realistic cellular responses; nevertheless, these data questioned the validity of the use of unsubstituted etheno adducts as reliable oxidative stress and nitro-PAH exposure biomarkers.
