Purification and Properties of Nucleotide Pyrophosphatase from Human Placenta1

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 to-wards 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, oligonucleo-tides, 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-l-propanol were inhibitory. Most of these properties are common to nucleotide pyrophospha-tases [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.