NTPDase

The involvement of releasable enzymes in the metabolism of extracellular nucleotides has been suggested to explain an increase in the capacity to metabolize ATP observed in some tissues following nerve stimulation (Todorov et al. 1996 Mihaylova-Todorova et al. 2002). Released enzymes resembling the E-NTPDases mentioned above seem to be able to convert released ATP to AMP. In some tissues (guinea pig but not rabbit vas deferens), the released enzymes also hydrolyse AMP into adenosine (see Westfall et al. 2002). 

Localization of ecto-5 ectonucleotidase close to NTPDases creates a very efficient system to produce adenosine from released ATP, favoring activation of adenosine receptors (Nitahara et al. 1995 Cunha et al. 1998 Sebastiao et al. 1999 Duarte-Araujo et al. 2004 see Matsuoka and Ohkubo 2004). This situation seems to prevail in the rat hippocampus and may explain the inhibition of synaptic transmission caused by ATP and ATP analogues (Cunha et al. 1998). 

The molecular mechanisms underlying the detrimental effects caused by aluminum have yet to be fully understood [31]. The toxicological mechanisms of aluminum in plants or in animals probably involve alterations in many enzyme activities. There is a large number of proteins which requires nucleoside phosphates as substrates or is regulated by nucleoside phosphates, therefore aluminum can potentially interfere with the normal functions of these proteins [18]. Thus, it is important to understand some reactions that involve aluminum and nucleotides. In this review we are going to focus on the alterations caused by this metal in some enzymes that hydrolyze or transfer phosphate groups of nucleotides, like NTPases, NTPDases, and kinases. 

NTPDases Nucleoside triphosphate diphosphohydrolases also known as apyrases,... 

Muthuvijayan, V., Gu, J., Lewis, R. S. 2009. Analysis of functionalized polyethylene terephthalate with immobilized NTPDase and cysteine, 5(9) ... 

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