- Fluorescent guanosine nucleotide analogs suitable for photoaffinity labeling experiments
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The synthesis and properties of strongly fluorescent derivatives of inosine and its nucleotides are described. Reaction of 2 chloro inosinic acid with sodium azide leads to a product bearing the tetrazole ring between position 2 and 3. Methylation at N1 was effected with dimethyl sulfate. The corresponding nucleosides and their 5' triphosphates were also prepared. Only the non methylated series is at equilibrium with small concentrations of their azido forms, and can be photolyzed by wavelengths above 300 nm. Both series are strongly fluorescent, their emission and excitation fluorescence spectra, as well as their quantum yields being measured. The nucleoside 5' triphosphates are able to initiate and sustain polymerization of porcine brain tubulin.
- Wiegand,Kaleja
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- Formation of 2-chloroinosine from guanosine by treatment of HNO2 in the presence of NaCl
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We investigated the reaction of Guo with nitrous acid in the presence of NaCl. When 1 mM Guo was incubated with 100 mM NaNO2 and 2 M NaCl in sodium acetate buffer at pH 3.2 and 37°C, 2-chloroinosine (2-Cl-Ino) was produced in addition to oxanosine (Oxo) and xanthosine (Xao). The yield of 2-Cl-Ino was 0.033 mM at an incubation time of 2 h. Under the same reaction conditions, GMP and dGuo gave rise to the corresponding 2-chloro derivatives with comparable yields. All the 2-chloro derivatives were fairly stable (t1/2>360 h) at physiological pH and temperature. To elucidate the reaction mechanism of the chlorination, the diazoate derivative of Guo, a reaction intermediate of the Guo-HNO2 system, was employed as a starting compound. When the diazoate was incubated with 2 M NaCl in a neutral solution, 2-Cl-Ino was produced in addition to Oxo and Xao. These results suggest that the 2-chloro derivatives can be produced from foodstuffs in the human stomach and may have potential importance as a carcinogen causing gastric cancer.
- Suzuki, Toshinori,Ide, Hiroshi,Yamada, Masaki,Morii, Takashi,Makino, Keisuke
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p. 2937 - 2941
(2007/10/03)
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