PT  - JOURNAL ARTICLE
AU  - MERILYN J. EDWARDS
AU  - M. HELEN MAGUIRE
TI  - Purification and Properties of Rat Heart 5'-Nucleotidase
DP  - 1970 Nov 01
TA  - Molecular Pharmacology
PG  - 641--648
VI  - 6
IP  - 6
4099  - http://molpharm.aspetjournals.org/content/6/6/641.short
4100  - http://molpharm.aspetjournals.org/content/6/6/641.full
SO  - Mol Pharmacol1970 Nov 01; 6
AB  - 5'-Nucleotidase (EC 3.1.3.5) has been purified 26-fold from rat heart and obtained substantially free of nonspecific phosphatase activity. The pH optimum for the enzyme was 7.6; at this pH, 7 mM Mg++ and 2 mM Ca++ caused 40% inhibition of 5'-nucleotidase activity, and 0.17-0.69 mM Mg++ was without effect on activity. The nucleoside triphosphates ATP, UTP, CTP, GTP, and ITP inhibited 5'-nucleotidase in a noncompetitive manner with respect to adenosine 5'-monophosphate. The AMP analogues adenosine 5'-phosphorothioate (AMPS) and 2-chloroadenosine 5'-monophosphate (2-chloro-AMP), which are vasodilators, and 2-methylthioadenosine 5'-monophosphate (2-methylthio-AMP), which has no vasodilatory properties, were all substrates of 5'-nucleotidase, with Michaelis constants similar to that of AMP. The maximum velocities of hydrolysis of AMPS, 2-chloro-AMP, and 2-methylthio-AMP were 36%, 79%, and 116%, respectively, of the maximum velocity for AMP. The rates of hydrolysis of these analogues by 5'-nucleotidase are considered in relation to their vasodilatory effects. ACKNOWLEDGMENT The authors wish to thank Dr. W. J. O’Sullivan of the Department of Medicine, University of Sydney, for his calculations of MgAMP concentrations.