Abstract
Purine nucleoside phosphorylase (PNP; EC 2.4.2.1) catalyzes the phosphorolysis of (d)guanosine or inosine to form the base (guanine or hypoxanthine) and (d)ribose-1-P; the enzyme has therefore been defined as catabolic (1,2). The enzyme may also be considered as biosynthetic, since the salvage of purines to form nucleotides is largely via a one step phosphoribosyltransferase reaction. Reports characterizing this enzyme have not been consistent. Based on the native Mr, the enzyme has been reported as a trimer, a dimer, or a monomer (references in #3). Also, some studies have reported negative cooperativity with phosphate (references in #4), or nucleosides (references in #4). Some ambiguity about the above results arose when other studies reported no cooperativity with phosphate, or with nucleosides (references in #4).
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References
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© 1991 Plenum Press, New York
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Traut, T.W., Ropp, P.A., Poma, A. (1991). Purine Nucleoside Phosphorylase: Allosteric Regulation of a Dissociating Enzyme. In: Harkness, R.A., Elion, G.B., Zöllner, N. (eds) Purine and Pyrimidine Metabolism in Man VII. Advances in Experimental Medicine and Biology, vol 309B. Springer, New York, NY. https://doi.org/10.1007/978-1-4615-7703-4_40
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DOI: https://doi.org/10.1007/978-1-4615-7703-4_40
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