Kinetic characterization of ATP diphosphohydrolase and 5'-nucleotidase activities in cells cultured from submandibular salivary glands of rats |
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Authors: | Henz Sandra Liana Ribeiro Cristiane Guimarães Rosa Aline Chiarelli Rafael Augusto Casali Emerson André Sarkis João José Freitas |
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Affiliation: | Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Avenida Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil. |
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Abstract: | The participation of ecto-ATP diphosphohydrolase (CD39; ecto-NTPDase) and ecto-5'-nucleotidase (CD73) activities in the nucleotide hydrolysis by salivary gland cells from rats was evaluated. We investigated the biochemical characteristics of these ectoenzymes in cells cultured from submandibular salivary glands of rats. The V(max) for the hydrolysis of ATP, ADP and AMP were 2275+/-153 (mean+/-SEM, n = 4), 941+/-96 (mean+/-SEM, n = 5) and 175+/-5 (mean+/-SEM, n = 5) nmol Pi liberated per min per mg of protein, respectively. The K(m) values for ATP, ADP and AMP were 224+/-8 microM (mean+/-SEM, n = 4), 163+/-15 microM (mean+/-SEM, n = 5) and 117+/-5 microM (mean+/-SEM, n = 5), respectively. The competition plot showed that ATP and ADP were hydrolyzed at the same active site on the enzyme. It may be postulated that the physiological role for this ecto-enzyme cascade is to terminate the action of the co-transmitter ATP, generating adenosine. |
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Keywords: | Ectonucleotidases Rat submandibular gland Nucleotide hydrolysis |
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