Isolation of N omega-phosphoarginine hydrolase from rat liver and its physical properties

N omega-Phosphoarginine hydrolase from rat liver cytosol was purified to apparent homogeneity on SDS-PAGE, by employing column chromatographies on Sephadex G-75, DEAE-cellulose, QAE-Toyopearl, and glutathione-2-pyridyl-disulfide-Superose. One milligram protein of the final preparation released 4 mumol/min of inorganic phosphate from N omega-phosphoarginine. The molecular mass on SDS-PAGE, the Stokes' radius and the sedimentation coefficient were estimated to be 17.3 kDa, 1.63 nm, and 2.0 s, respectively, indicating that this enzyme consists of a single peptide. The stability of the enzyme to heat depended on the buffers employed and treatment of the enzyme preparation in 50 mM Tris-HCl, pH 7.0 at 50 degrees C, reduced the hydrolytic activity with a decay constant of 0.099 per min.