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- Title
Polymerization of ADP-Ribose Pyrophosphatase: conversion mechanism of Mg<sup>2+</sup>-dependent ADP-Ribose Pyrophosphatase into Mg<sup>2+</sup>-independent form.
- Authors
Kim, Dae-Ki; Kim, Jong-Hyun; Song, Eun-Kyung; Han, Myung-Kwan; Kim, Jong-Suk
- Abstract
ADP-ribose pyrophosphatase (ADPRase) hydrolyzes ADP-ribose (ADPR) into AMP and ribose-5′-phosphate. It is classified into two groups, Mg 2+-dependent and Mg 2+-independent ADPRase, depending on its Mg 2+ requirement. Here, we purified Mg 2+-dependent ADPRase from rabbit liver and examined what factors affect Mg 2+ requirement. The purified enzyme showed a single band with the molecular weight of 34 kDa on SDS-PAGE both in the presence and absence of 2-mercaptoethanol. The molecular weight of the native enzyme calculated by gel filtration was 68 kDa, indicating that ADPRase is a dimer made up of two identical subunits. Mg2+-dependent ADPRase with the highest ADPR affinity had a K m of 160±10 μM and a pH optimum of around pH 9.5. Treatment of the purified ADPRase with heated cytosol fractions at 37°C for 3 h caused some changes in the chemical properties of the enzyme, including an increase in molecular weight, a decrease in solubility, and a loss of Mg2+-depen-dency. The molecular weight of the cytosol-treated ADPRase measured by gel filtration was over 420 kDa, suggesting, for the first time, that ADPRase could be polymerized by undefined cytoplasmic factors, and that polymerization is accompanied by changes in the solubility and metal ion dependency of the enzyme.
- Publication
Archives of Pharmacal Research, 2003, Vol 26, Issue 10, p826
- ISSN
0253-6269
- Publication type
Article
- DOI
10.1007/BF02980028