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Ebselen is a potent non-competitive inhibitor of extracellular nucleoside diphosphokinase

Semianrio-Vidal, Lucia and van Hesuden, Catharina and Mugesh, Govindasamy and Lazarowski, Eduardo Rodolfo (2010) Ebselen is a potent non-competitive inhibitor of extracellular nucleoside diphosphokinase. In: Purinergic Signalling, 6 (4). pp. 383-391.

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Official URL: http://www.springerlink.com/content/5263183l354628...

Abstract

Nucleoside di- and triphosphates and adenosine regulate several components of the mucocilairy clearance process (MCC) that protects the lung against infections, via activation of epithelial purinergic receptors. However, assessing the contribution of individual nucleotides to MCC functions remains difficult due to the complexity of the mechanisms of nucleotide release and metabolism. Enzymatic activities involved in the metabolism of extracellular nucleotides include ecto-ATPases and secreted nucleoside diphosphokinase (NDPK) and adenyl kinase, but potent and selective inhibitors of these activities are sparse. In the present study, we discovered that ebselen markedly reduced NDPK activity while having negligible effect on ecto-ATPase and adenyl kinase activities. Addition of radiotracer gamma P-32]ATP to human bronchial epithelial (HBE) cells resulted in rapid and robust accumulation of P-32]-inorganic phosphate ((32)Pi). Inclusion of UDP in the incubation medium resulted in conversion of gamma P-32]ATP to P-32]UTP, while inclusion of AMP resulted in conversion of gamma P-32]ATP to P-32]ADP. Ebselen markedly reduced P-32]UTP formation but displayed negligible effect on (32)Pi or P-32]ADP accumulations. Incubation of HBE cells with unlabeled UTP and ADP resulted in robust ebselen-sensitive formation of ATP (IC50=6.9 +/- 2 mu M). This NDPK activity was largely recovered in HBE cell secretions and supernatants from lung epithelial A549 cells. Kinetic analysis of NDPK activity indicated that ebselen reduced the V-max of the reaction (K-i=7.6 +/- 3 mu M), having negligible effect on KM values. Our study demonstrates that ebselen is a potent noncompetitive inhibitor of extracellular NDPK.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Springer.
Keywords: Nucleoside diphosphokinase; Ebselen; Extracellular nucleotides; Nucleotide release; Lung epithelial cells
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 29 Mar 2011 11:48
Last Modified: 11 Aug 2011 10:03
URI: http://eprints.iisc.ernet.in/id/eprint/36334

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