Partial purification and properties of an AMP-specific soluble 5'-nucleotidase from pigeon heart.
A soluble 5'-nucleotidase was purified 200-fold from pigeon heart. The enzyme (1) had an apparent molecular mass close to 150 kDa, (2) had a neutral pH optimum and hydrolysed a wide range of nucleoside 5'-monophosphates with a 15-fold preference for AMP over IMP, (3) at near-physiological concentrations of AMP was activated by ADP but not by ATP, (4) was inhibited by high Mg2+ concentration and high ionic strength, (5) was weakly inhibited by p-nitrophenol phosphate and Pi, and (6) was non-competitively inhibited more potently by 5'-deoxy-5'-isobutylthioinosine than by 5'-deoxy-5'-isobutylthioadenosine, but not by [alpha,beta-methylene]ADP. The data show that the enzyme is distinct from the ecto-5'-nucleotidase and from the previously purified IMP-specific 5'-nucleotidase. They also predict that the enzyme is activated during ATP catabolism and hence will generate a more-than-linear increase in the adenosine-formation rate in response to an increase in cytosolic AMP concentration.
Skladanowski
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Department of Cardiology, University of Wales College of Medicine, Heath Park, Cardiff, U.K.
Newby
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D015720:5'-Nucleotidase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D010856:Columbidae / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007291:Inosine Monophosphate / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology*; D009994:Osmolar Concentration; D012995:Solubility; D013379:Substrate Specificity
D007291:Inosine Monophosphate; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D015720:5'-Nucleotidase; D008274:Magnesium