| Abstract: | Nucleotide pyrophosphatase was purified from human placenta to near homogeneity with a specific activity of about 500-fold over the Triton extract of the homogenate. Purification was achieved most effectively by successive chromatographic steps with AMP-agarose and ADP-agarose columns, based on the affinity of the enzyme towards 5'-adenylate and adenosine 3',5'-diphosphate, and a lectin-Sepharose column, based on the glycoprotein nature of the enzyme. The purified enzyme was found to be essentially homogeneous on SDS-polyacrylamide gel electrophoresis with a mobility corresponding to 130K. The purified enzyme was found to hydrolyze a wide variety of nucleotides, i.e. 3'-phosphoadenosine 5'-phosphosulfate (PAPS), adenosine 5'-phosphosulfate (APS), NADH, ATP, nucleotide sugars, oligonucleotides, and p-nitrophenyl-thymidine 5'-phosphate (PNTP). From the oligonucleotides, the enzyme produced 5'-phosphates. Mg2+ was required for full activity. Glycine and sulfhydryl compounds such as 2-mercaptoethanol and 2,3-dimercapto-1-propanol were inhibitory. Most of these properties are common to nucleotide pyrophosphatases [EC 3.6.1.9] and type I (5'-phosphate forming) phosphodiesterases [EC 3.1.4.1] from various sources. The relevance of this enzyme to a unique genetic disease, Lowe's syndrome, is discussed. |
