AI Article Synopsis
- The study investigated the role of ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) in hydrolyzing nucleotides in rat salivary gland cells, using a specific substrate, p-Nitrophenyl 5'-thymidine monophosphate (p-Nph-5'-TMP).
- Primary cell cultures demonstrated significant E-NPP enzyme activity, which was influenced by factors like metal ions and pH levels, and specific measurements indicated the enzyme's affinity and maximum activity rates.
- The research suggests that E-NPP works alongside other ecto-enzymes to manage ATP's effects in salivary glands by converting it to adenosine, playing a crucial role in cellular signaling.
Article Abstract
The participation of ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activity in the nucleotide hydrolysis by salivary gland cells of rats was evaluated using p-nitrophenyl 5'-thymidine monophosphate (p-Nph-5'-TMP) as a substrate for this enzyme. We investigated the biochemical characteristics of this ectoenzyme in cells cultured from submandibular salivary glands of rats. Primary cell cultures demonstrated ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activities, which could be observed by extracellular hydrolysis of p-Nph-5'-TMP and other biochemical characteristics such as dependence of metal ions, dependence of pH alkaline and inactivation by a metal ion chelator. The Km value for the hydrolysis of p-Nph-5'-TMP was 280.7+/-34.2 microM (mean+/-S.D., n=4) and Vmax was 721.31+/-225nmol p-nitrophenol/min/mg (mean+/-S.D., n=4). We suggest that E-NPP is co-localized with an ecto-ATP diphosphohydrolase/ecto-NTPDase and an ecto-5'-nucleotidase, since these enzymes probably act under different conditions. It may be postulated that the physiological role for these ecto-enzymes is to terminate the action of the co-transmitter ATP, generating adenosine.
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| http://dx.doi.org/10.1016/j.archoralbio.2007.03.006 | DOI Listing |
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