Purification and properties of a nucleotide pyrophosphatase from lentil seedlings.

A nucleotide pyrophosphatase (EC 3.6.1.9) was purified to homogeneity from lentil seedlings. The enzyme is a single polypeptide chain of 75 +/- 2 kDa that exhibits hydrolytic activities toward pyrophosphate linkages of several substrates. Reduced and oxidized forms of NAD(P) were shown to be hydrolyzed to nicotinamide mononucleotide and AMP. Other dinucleotides such as FAD and dinucleoside oligophosphates were hydrolyzed as well, but with lower efficiency. Pyrophosphatase activity was increased in the presence of divalent cations such as Ca2+, Mg2+, and Mn2+, whereas Cu2+, Zn2+, and Ni2+ ions inhibited this activity. The active site in the enzyme was not defined, but histidine residue(s) seemed to be crucial for the enzymatic activity.