964-21-6Relevant articles and documents
Direct Alkylation of Deoxyguanosine by Azaserine Leads to O6-Carboxymethyldeoxyguanosine
Geisen, Susanne M.,Aloisi, Claudia M. N.,Huber, Sabrina M.,Sandell, Emma S.,Escher, Nora A.,Sturla, Shana J.
, p. 1518 - 1529 (2021/06/28)
The O6-alkylguanosine adduct O6-carboxymethyldeoxyguanosine (O6-CMdG) has been detected at elevated levels in blood and tissue samples from colorectal cancer patients and from healthy volunteers after consuming red meat. The diazo compound l-azaserine leads to the formation of O6-CMdG as well as the corresponding methyl adduct O6-methyldeoxyguanosine (O6-MedG) in cells and is therefore in wide use as a chemical probe in cellular studies concerning DNA damage and mutation. However, there remain knowledge gaps concerning the chemical basis of DNA adduct formation by l-azaserine. To characterize O6-CMdG formation by l-azaserine, we carried out a combination of chemical and enzymatic stability and reactivity studies supported by liquid chromatography tandem mass spectrometry for the simultaneous quantification of O6-CMdG and O6-MedG. We found that l-azaserine is stable under physiological and alkaline conditions as well as in active biological matrices but undergoes acid-catalyzed hydrolysis. We show, for the first time, that l-azaserine reacts directly with guanosine (dG) and oligonucleotides to form an O6-serine-CMdG (O6-Ser-CMdG) adduct. Moreover, by characterizing the reaction of dG with l-azaserine, we demonstrate that O6-Ser-CMdG forms as an intermediate that spontaneously decomposes to form O6-CMdG. Finally, we quantified levels of O6-CMdG and O6-MedG in a human cell line exposed to l-azaserine and found maximal adduct levels after 48 h. The findings of this work elucidate the chemical basis of how l-azaserine reacts with deoxyguanosine and support its use as a chemical probe for N-nitroso compound exposure in carcinogenesis research, particularly concerning the identification of pathways and factors that promote adduct formation.
Enzymatic Synthesis of Therapeutic Nucleosides using a Highly Versatile Purine Nucleoside 2’-DeoxyribosylTransferase from Trypanosoma brucei
Pérez, Elena,Sánchez-Murcia, Pedro A.,Jordaan, Justin,Blanco, María Dolores,Manche?o, José Miguel,Gago, Federico,Fernández-Lucas, Jesús
, p. 4406 - 4416 (2018/09/14)
The use of enzymes for the synthesis of nucleoside analogues offers several advantages over multistep chemical methods, including chemo-, regio- and stereoselectivity as well as milder reaction conditions. Herein, the production, characterization and utilization of a purine nucleoside 2’-deoxyribosyltransferase (PDT) from Trypanosoma brucei are reported. TbPDT is a dimer which displays not only excellent activity and stability over a broad range of temperatures (50–70 °C), pH (4–7) and ionic strength (0–500 mM NaCl) but also an unusual high stability under alkaline conditions (pH 8–10). TbPDT is shown to be proficient in the biosynthesis of numerous therapeutic nucleosides, including didanosine, vidarabine, cladribine, fludarabine and nelarabine. The structure-guided replacement of Val11 with either Ala or Ser resulted in variants with 2.8-fold greater activity. TbPDT was also covalently immobilized on glutaraldehyde-activated magnetic microspheres. MTbPDT3 was selected as the best derivative (4200 IU/g, activity recovery of 22 %), and could be easily recaptured and recycled for >25 reactions with negligible loss of activity. Finally, MTbPDT3 was successfully employed in the expedient synthesis of several nucleoside analogues. Taken together, our results support the notion that TbPDT has good potential as an industrial biocatalyst for the synthesis of a wide range of therapeutic nucleosides through an efficient and environmentally friendly methodology.
Synthesis and characterization of DNA containing O6-carboxymethylguanine
Xu, Yao-Zhong
, p. 6075 - 6081 (2007/10/03)
O6-Carboxymethylguanine was formed in DNA treated with N-nitrosoglycocholic acid and believed to be implicated in human gastrointestinal and colorectal tumour. An efficient method is presented here for synthesis of oligodeoxynucleotides containing O6-carboxy-methylguanine at pre-determined positions. The synthetic protocol also allows for production of oligomers containing O6-aminocarbonyl-methylguanine. These guanine-modified oligomers have been fully characterized and could provide a useful tool for biological studies of these modified bases. (C) 2000 Elsevier Science Ltd.
