Guanine 9-ethyl

Nucleobases, including 9-methyl-, 9-ethyl-, 1,9-dimethyl-guanine and 2-amino-6-methoxy-9-methylpurine, form complexes of the type Au(N)Cl3 when reacted with [AuCU] in water at pH 3—4. Binding of a AuCh unit to the N (7) position of the purine ring was confirmed by X-ray crystallography [26]. 

The antiviral nucleotide analogue 9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine also uses its N7 as a major binding site and forms a N7-phosphonate macrochelate (698).1833 Another antiviral analogue of 2 -deoxyguanosine, acyclovir (9-[(2-hydroxyethoxy)-methyl]guanine) forms with Ni11 a bis-complex with two N7 coordinated in trans position to each other.1834... 

If a DNA adduct involves the nitrogen or oxygen atoms involved in base-pairing, and the adducted DNA is not repaired, base substitution can result. Adducts can be small, such as the simple addition of methyl or ethyl groups, or they can be very bulky, owing to reaction with multiringed structures. The most vulnerable base is guanine, which can form adducts at several of its atoms (e.g., N7, C8, O6 and exocyclic N2) (Venitt and Parry, 1984). Adducts can form links between adjacent bases on the same strand (intrastrand cross-links) and can form interstrand crosslinks between each strand of double-stranded DNA. 

Hsie, A.W., Brimer, P.A., Mitchell, T.J. and Gosslee, D.G. (1975). The dos-response relationship for ethyl methane sulfonate-induced mutation at the hypoxanthine-guanine phosphor-ibosyl transferase locus in Chinese hamster ovary cells. Somatic Cell Genet. 1 247-261. 

S-Adenosyl ethionine carries out ethylation reactions or ethyl transfer, and this is presumably involved in the carcinogenesis. Administration of ethionine to animals leads to the production of ethylated bases such as ethyl guanine. This may account for the observed inhibition of RNA polymerase and consequently of RNA synthesis. Incorporation of abnormal bases into nucleic acids and the production of impaired RNA may also lead to the inhibition of protein synthesis and misreading of the genetic code. 

The four standard PNA monomers [adenine (A), cytosine (C), guanine (G), and thymine (T)] used in solid-phase synthesis are commercially available. However, three additional monomers used routinely are not. The syntheses of these monomers are given in Sections 12.6.1.1-12.6.1.4 together with the synthesis of the /V-[2-(/er/-butoxycarbonylamino)-ethyl] glycine backbone. 

Alkylating agents that can cause methylation and ethylation of bases. Guanine, for example, reacts with dimethylsulphate to form o-methylguanine. 

Amino-6-chloro-9-[2-(2,2-dimethyl-l,3-dioxan-5-yl)-ethyl]purine (0.59 g, 1.9 mmol) in hydrochloric acid (1.0 M, 4 ml) was stirred at 60°C for 24 hours. The solution was diluted with water and neutralised with Amberlite IR 45. The mixture was filtered, the resin washed with water and the solvent evaporated under reduced pressure. The residue was recrystallised from water to afford 9-(4-hydroxy-3-hydroxymethylbut-l-yl)guanine (238 mg, 49%), melting point 275°-277°C. 

ADDUCT A chemical addition product. For example, when the mutagenic alkylating agent ethyl methanesulfonate reacts with DNA, any of the normal bases in DNA (i.e., adenine, thymine, guanine, and cytosine) may be converted into adducts, such as N7-ethylguanine and N3-ethylcytosine. 

A. Fidder, D. Noort, L.P.A. de Jong, H.P. Ben-schop and A.G. Hulst, N7-(2-Hydroxyethylthio-ethyl)-guanine a novel urinary metabolite following exposure to sulfur mustard, Arch. Toxicol., 70, 854-855 (1996). 

In contrast, the G-C combination occurs only in the Watson-Crick configuration GC23 (Fig. 16.13). This is observed in 9-ethyl-guanine-1-methylcytosine [EGMCYT101, and in 9-ethylguanine-1-methyl-5-bromocytosine [EGUMBC]. 

Acid amides have occasionally, like formamide, been used to produce 8-substituted purines. Acetamide and 2,4,5-triamino-6-oxo-l,6-dihydropyrimidine afforded 8-methyl-guanine (60JA2633) and 8-methyl- or ethyl-xanthines resulted from acetamide or propion-amide and 4,5-diamino-2,6-dioxo-l,2,3,6-tetrahydropyrimidine (53CB333). Diamides such... 

In particular, chemical carcinogenesis by compounds such as diethyinitrosamine, 1-ethyl-l-ni-trosourea, ethyl methanesulfonate, or 3,3-dialkyl-l-aryltriazenes is the result of alkylation reactions of various nucleobases, mainly guanine, within DNA. ... 

The alkylation of guanine differs in almost every respect from that of adenine. Detailed examination of an alkylation mixture obtained from the action of ethyl methanesulfonate on a sodium hydroxide solution of guanine at 40 shows that the products include 9-methyl-, 7-methyl-, 3-methyl-, and 1-methylguanine. Further alkylation of 1-methylguanine leads to a 1,7,9-trimcthylated guanine which is isolated as the picrate. " - ... 

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