Purine nucleoside phosphorylase activity in rat cerebrospinal fluid.
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.
Silva
Rafael Guimarães
RG
Grupo de Microbiologia Molecular e Funcional, Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, RS, Brazil.
Santos
Diógenes Santiago
DS
Basso
Luiz Augusto
LA
Oses
Jean Pierre
JP
Wofchuk
Susana
S
Portela
Luis Valmor Cruz
LV
Souza
Diogo Onofre
DO
D000818:Animals; D004789:Enzyme Activation; D004795:Enzyme Stability / Q000502:physiology; D007700:Kinetics; D011683:Purine-Nucleoside Phosphorylase / Q000134:cerebrospinal fluid*; D051381:Rats; D013997:Time Factors
D011683:Purine-Nucleoside Phosphorylase