Cytosolic purine nucleoside phosphorylase (PNP) trimer catalyzes the reversible reaction of hypoxanthine with ribose 1-phosphate or deoxyribose 1-phosphate to form inosine or deoxyinosine and orthophosphate (Ealick et al. 1990; Wiginton et al. 1980). While PNP is active with either ribose 1-phosphate or deoxyribose 1-phosphate in vitro, levels of deoxyribose 1-phosphate are normally low in vivo, limiting the extent of this reaction. PNP deficiency in vivo is associated with defects in purine metabolism and leads to immunodeficiency (Williams et al. 1987).
Williams, SR, Gekeler, V, McIvor, RS, Martin, Jr, DW
Hutton, JJ, Wiginton, DA, Coleman, MS
Cook, WJ, Habash, J, Greenhough, TJ, Babu, YS, Carter, DC, Parks, Jr, RE, Rule, SA, Bugg, CE, Stoeckler, JD, Chen, SF, Ealick, SE, Helliwell, JR
purine-nucleoside phosphorylase activity of PNP trimer [cytosol]
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