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Literature summary extracted from

  • Stachelska-Wierzchowska, A.; Wierzchowski, J.; Gorka, M.; Bzowska, A.; Wielgus-Kutrowska, B.
    Tri-cyclic nucleobase analogs and their ribosides as substrates of purine-nucleoside phosphorylases II guanine and isoguanine derivatives (2019), Molecules, 24, 1493 .
    View publication on PubMedView publication on EuropePMC

Application

EC Number Application Comment Organism
2.4.2.1 synthesis important application of PNP is in chemo-enzymatic synthesis of bioactive nucleoside analogues, utilizing various types of PNP among others. This application may be extended to tricyclic nucleobase analogues, particularly to adenine, isoguanine, and guanine derivatives. In particular, N9-D-riboside of can be obtained quantitatively from 1,N2-ethenoguanine, and N9-beta-D- and N7-beta-D-ribosides of 1,N6-etheno-isoguanine as a mixture, using the Escherichia coli PNP as a biocatalyst Escherichia coli

Protein Variants

EC Number Protein Variants Comment Organism
2.4.2.1 D204N site-directed mutagenesis, the enzymatic ribosylation of 1,N6-etheno-isoguanine using Escherichia coli PNP wild-type and D204N mutant enzymes gives different products, which are identified on the basis of NMR analysis and comparison with the product of the isoguanosine reaction with chloroacetic aldehyde, which gives an essentially single compound, identified unequivocally as N9-riboside Escherichia coli

Inhibitors

EC Number Inhibitors Comment Organism Structure
2.4.2.1 N2,3-etheno-O6-methylguanine is a poor substrate, it competitively competes with guanine in the ribosylation process, acting as quasi inhibitor of the Escherichia coli PNP Escherichia coli
2.4.2.1 N2,3-ethenoguanine exhibits moderate, possibly competitive inhibition of Escherichia coli PNP Escherichia coli

Organism

EC Number Organism UniProt Comment Textmining
2.4.2.1 Escherichia coli P45563
-
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.4.2.1 1,N2-ethenoguanine + alpha-D-ribose 1-phosphate
-
 Escherichia coli 1,N2-ethenoguanosine + phosphate
-
 r
2.4.2.1 1,N6-etheno-isoguanine + alpha-D-ribose 1-phosphate isoguanine is 2-hydroxy-6-aminopurine and showing a solvent-induced keto-enol tautomerism Escherichia coli 1,N6-etheno-isoguanosine + phosphate
-
 r
2.4.2.1 additional information etheno-derivatives of guanine, O6-methylguanine, and isoguanine are prepared and examined as potential substrates of purine-nucleoside phosphorylase in the reverse (synthetic) pathway. 1,N2-ethenoguanine and 1,N6-etheno-isoguanine are excellent substrates for purine-nucleoside phosphorylase (PNP) from Escherichia coli, while O6-methyl-N2,3-ethenoguanine exhibits moderate activity with this enzyme. The ribosylation reaction is fully reversible by the addition of a phosphate buffer up to a concentration of about 5 mM. The inability of the enzyme to ribosylate N2,3-ethenoguanine is not due to geometric hindrance, but rather should be ascribed to unfavorable energetic factors, in accordance with previous reports about the relative instability of the glycosidic bond in this compound. N2,3-etheno-O6-methylguanine is a poor substrate, it competitively competes with guanine in the ribosylation process, acting as quasi inhibitor of the Escherichia coli PNP. 6-Aminopurine ribosides, not possessing a mobile proton at the N1 position, do not react with trimeric forms of PNP Escherichia coli ?
-
-
2.4.2.1 N2,3-etheno-O6-methylguanine + alpha-D-ribose 1-phosphate
-
 Escherichia coli N2,3-etheno-O6-methylguanosine + phosphate
-
 r
2.4.2.1 N2,3-ethenoguanine + alpha-D-ribose 1-phosphate
-
 Escherichia coli N2,3-ethenoguanosine + phosphate
-
 r
2.4.2.1 O6-methyl-N2,3-ethenoguanine + alpha-D-ribose 1-phosphate
-
 Escherichia coli O6-methyl-N2,3-ethenoguanosine + phosphate
-
 r

Subunits

EC Number Subunits Comment Organism
2.4.2.1 trimer
-
 Escherichia coli

Synonyms

EC Number Synonyms Comment Organism
2.4.2.1 PNP-II
-
 Escherichia coli
2.4.2.1 purine-nucleoside phosphorylases II
-
 Escherichia coli

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
2.4.2.1 25
-
 assay at Escherichia coli

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
2.4.2.1 7.3
-
 assay at Escherichia coli

Ki Value [mM]

EC Number Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
2.4.2.1 0.0075
-
 N2,3-etheno-O6-methylguanine pH 7.3, 25°C Escherichia coli
2.4.2.1 0.038
-
 N2,3-ethenoguanine pH 7.3, 25°C Escherichia coli

General Information

EC Number General Information Comment Organism
2.4.2.1 additional information possible tautomeric forms of 1,N6-etheno-isoguanine. The main reason for slow ribosylation and the resistance of the parent N2,3-ethenoguanine to the enzymatic ribosylation is probably unfavorable energetics Escherichia coli