959669-55-7Relevant academic research and scientific papers
Site-Selective ribosylation of fluorescent nucleobase analogs using purine-Nucleoside phosphorylase as a catalyst: effects of point mutations
Stachelska-Wierzchowska, Alicja,Wierzchowski, Jacek,Bzowska, Agnieszka,Wielgus-Kutrowska, Beata
, (2016/02/05)
Enzymatic ribosylation of fluorescent 8-azapurine derivatives, like 8-azaguanine and 2,6-diamino-8-azapurine, with purine-nucleoside phosphorylase (PNP) as a catalyst, leads to N9, N8, and N7-ribosides. The final proportion of the products may be modulated by point mutations in the enzyme active site. As an example, ribosylation of the latter substrate by wild-type calf PNP gives N7- And N8-ribosides, while the N243D mutant directs the ribosyl substitution at N9- And N7-positions. The same mutant allows synthesis of the fluorescent N7-β-D-ribosyl-8-azaguanine. The mutated form of the E. coli PNP, D204N, can be utilized to obtain non-typical ribosides of 8-azaadenine and 2,6-diamino-8-azapurine as well. The N7- And N8-ribosides of the 8-azapurines can be analytically useful, as illustrated by N7-β-D-ribosyl-2,6-diamino-8-azapurine, which is a good fluorogenic substrate for mammalian forms of PNP, including human blood PNP, while the N8-riboside is selective to the E. coli enzyme.
Enzymatic synthesis of highly fluorescent 8-azapurine ribosides using a purine nucleoside phosphorylase reverse reaction: Variable ribosylation sites
Stachelska-Wierzchowska, Alicja,Wierzchowski, Jacek,Wielgus-Kutrowska, Beata,Mikleusevic, Goran
, p. 12587 - 12598 (2013/11/06)
Various forms of purine-nucleoside phosphorylase (PNP) were used as catalysts of enzymatic ribosylation of selected fluorescent 8-azapurines. It was found that the recombinant calf PNP catalyzes ribosylation of 2,6-diamino-8-azapurine in a phosphate-free medium, with ribose-1-phosphate as ribose donor, but the ribosylation site is predominantly N7 and N8, with the proportion of N8/N7 ribosylated products markedly dependent on the reaction conditions. Both products are fluorescent. Application of the E. coli PNP gave a mixture of N8 and N9-substituted ribosides. Fluorescence of the ribosylated 2,6-diamino-8-azapurine has been briefly characterized. The highest quantum yield, ~0.9, was obtained for N9-β-D-riboside (λmax 365 nm), while for N8-β-D-riboside, emitting at ~430 nm, the fluorescence quantum yield was found to be close to 0.4. Ribosylation of 8-azaguanine with calf PNP as a catalyst goes exclusively to N9. By contrast, the E. coli PNP ribosylates 8-azaGua predominantly at N9, with minor, but highly fluorescent products ribosylated at N8/N7.
