5′-nucleotidase of chicken liver

Abstract

1. 1.|5′-Nucleotidase (5′-ribonucleotide phosphophydrolase, EC 3.1.3.5) was partially purified from chicken liver. This is the first time it has been possible to obtain 5′-nucleotidase from the hepatic tissue of uricotelic animals and it was found to be kinetically distinct from 5′-nucleotidases obtained from other sources. 2. 2.|5′-Mononucleotides having a keto group at position 6 in the purine base are the most active substrates of this enzyme. 5′-IMP is the most active substrate among the 5′-nucleotides tested, and it is about 10 times more active than 5′-AMP. 3. 3.|This enzyme has an optimum pH at 6.5 and requires divalent metal ions. In the absence of divalent metal ions, the enzyme is almost inactive. 4. 4.|Inosino, guanosine p-chloromercuribenzoate (PCMB) and NaF inhibit this enzyme. Of these inhibitors, PCMB was found to be the most potent. 5. 5.|The general properties of the enzyme are described, and its possible metabolic function is discussed.