Application | Comment | Organism |
---|---|---|
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 | Comment | Organism |
---|---|---|
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 | Comment | Organism | Structure |
---|---|---|---|
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 | |
N2,3-ethenoguanine | exhibits moderate, possibly competitive inhibition of Escherichia coli PNP | Escherichia coli |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Escherichia coli | P45563 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
1,N2-ethenoguanine + alpha-D-ribose 1-phosphate | - |
Escherichia coli | 1,N2-ethenoguanosine + phosphate | - |
r | |
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 | |
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 | ? | - |
- |
|
N2,3-etheno-O6-methylguanine + alpha-D-ribose 1-phosphate | - |
Escherichia coli | N2,3-etheno-O6-methylguanosine + phosphate | - |
r | |
N2,3-ethenoguanine + alpha-D-ribose 1-phosphate | - |
Escherichia coli | N2,3-ethenoguanosine + phosphate | - |
r | |
O6-methyl-N2,3-ethenoguanine + alpha-D-ribose 1-phosphate | - |
Escherichia coli | O6-methyl-N2,3-ethenoguanosine + phosphate | - |
r |
Subunits | Comment | Organism |
---|---|---|
trimer | - |
Escherichia coli |
Synonyms | Comment | Organism |
---|---|---|
PNP-II | - |
Escherichia coli |
purine-nucleoside phosphorylases II | - |
Escherichia coli |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7.3 | - |
assay at | Escherichia coli |
Ki Value [mM] | Ki Value maximum [mM] | Inhibitor | Comment | Organism | Structure |
---|---|---|---|---|---|
0.0075 | - |
N2,3-etheno-O6-methylguanine | pH 7.3, 25°C | Escherichia coli | |
0.038 | - |
N2,3-ethenoguanine | pH 7.3, 25°C | Escherichia coli |
General Information | Comment | Organism |
---|---|---|
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 |