Abstract
Human erythrocytes contain a cytosolic purine 5′-nucleotidase (5′-Nase) (Bontemps et al., Adv. Exp. Med. Biol. 195B:283–90, 1986; Biochem. J. 250:687–96, 1988) which, similarly to other cytosolic 5′-Nases, is more active on IMP and GMP than on AMP, is stimulated by ATP and, in addition, by glycerate-2,3-bisphosphate (2,3-DPG), the main phosphate ester in human erythrocytes. Both stimulators increase activity to the same extent at saturating concentrations, but 2,3-DPG is more potent than ATP at subsaturating concentrations. To investigate if 2,3-DPG was able to stimulate cytosolic 5′-Nase in other tissues, studies were performed on high-speed supernatants, freed from small molecules by dialysis or by filtration on G-25. 5′-Nase activity was measured at pH 7.2 by release of labelled nucleosides and bases from 0.2 mM [814C]-IMP. At 5 mM, 2,3-DPG was found to stimulate the activity of cytosolic purine 5′-Nase to the same extent as 5 mM ATP, in liver, cardiac and skeletal muscle, brain, spleen and erythrocytes from rat, and in human polymorphonuclear leukocytes, mixed peripheral blood lymphocytes and platelets. Depending on the tissue, maximal stimulation varied between 2- and 14-fold. 2,3-DPG was little hydrolyzed in the various preparations and was without effect on the membranous 5′-Nase. 2,3-DPG is thus a common stimulator of cytosolic purine 5′-Nase of various tissues and can be used to identify and reveal this enzymic activity in crude preparations.
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Bontemps, F., Vincent, M., Van Den Bergh, F. et al. 15 STIMULATION BY GLYCERATE-2, 3-BISPH0SPHATE: A COMMON PROPERTY OF CYTOSOLIC PURINE 5′-NUCLEOTIDASES IN VARIOUS TISSUES. Pediatr Res 24, 113 (1988). https://doi.org/10.1203/00006450-198807000-00039
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DOI: https://doi.org/10.1203/00006450-198807000-00039