Purine Nucleoside Phosphorylase Activity in Rat Cerebrospinal Fluid |
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Authors: | Guimarães Silva Rafael Santiago Santos Diógenes Augusto Basso Luiz Pierre Oses Jean Wofchuk Susana Valmor Cruz Portela Luis Onofre Souza Diogo |
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Affiliation: | Grupo de Microbiologia Molecular e Funcional, Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, RS, Brazil. |
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Abstract: | The sequential hydrolysis of purines is present in rat CSF and generates nucleosides as inosine and guanosine that are usual substrates for purine nucleoside phosphorylase (PNP). PNP catalyzes phosphorolysis of the purine nucleosides and deoxynucleosides releasing purine bases. Here we investigated the presence of PNP in CSF of rats using: i) a specific chromophoric analogue of nucleosides, 2-amino-6-mercapto-7-methylpurine ribonucleoside (MESG), and ii) an inhibitor of PNP activity, immucillin-H. Additionally, we performed a preliminary kinetic characterization (K(M): Henry-Michaelis-Menten constant; V: maximal velocity) for MESG and inorganic phosphate (Pi). The values of K(M) and V for MESG (n = 3, mean+/-SD) were 142.5+/-29.5 microM and 0.0102+/-0.0006 U mg(-1), respectively. For Pi (n=3, mean+/-SD), the K(M) values and V were 186.8+/-43.7 microM and 0.0104+/-0.0016 U mg(-1), respectively. The results indicated that PNP is present in rat CSF and provided a preliminary kinetic characterization. |
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Keywords: | CSF guanosine inosine PNP |
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