Nucleoside Phosphorylases make N7-xanthosine
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View abstract on PubMed
Summary
This summary is machine-generated.Enzymes typically attach nucleosides to purine bases at a specific site (N9). However, nucleoside phosphorylases also create a different form, N7-xanthosine, revealing these enzymes are not perfect catalysts.
Area Of Science
- Biochemistry
- Enzymology
- Natural Product Biosynthesis
Background
- Nucleoside-processing enzymes are highly evolved with established regioselectivity.
- Glycosylation of purine nucleobases predominantly occurs at the N9 position.
Purpose Of The Study
- To investigate exceptions to the N9 regioselectivity in nucleoside glycosylation.
- To characterize a novel ribosylation regioisomer of xanthosine.
Main Methods
- Enzymatic assays using wild-type nucleoside phosphorylases.
- Spectroscopic analysis of the synthesized nucleoside.
- Determination of physicochemical properties, including absorption spectra and phosphorolysis equilibrium.
Main Results
- Wild-type nucleoside phosphorylases were found to produce N7-xanthosine, a regioisomer of xanthosine.
- N7-xanthosine exhibits atypical properties: redshifted absorption spectra, high phosphorolysis equilibrium constant, and low acidity.
- This represents a deviation from the expected N9 glycosylation.
Conclusions
- The biosynthesis of N7-xanthosine demonstrates that even highly evolved enzymes from primary metabolism can be imperfect catalysts.
- This finding challenges the paradigm of perfect regioselectivity in nucleoside processing.
- A previously unknown natural product, N7-xanthosine, has been identified and characterized.
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