Characterization of Nω‐phosphoarginine hydrolase from rat liver

N ω‐Phosphoarginine hydrolase from rat liver hydrolyzed Nω‐phosphoarginine into arginine and inorganic phosphate, whereas it did not release inorganic phosphate from 19 other phosphorylated compounds containing a N‐P bond, an O‐P bond or a C‐P bond. In addition, it was not able to transfer the phosphoryl moiety from Nω‐phosphoarginine to ADP. These results indicated that this enzyme was distinct from both phosphoamidase and arginine kinase. Its properties were as follows: thiol compounds were essential for its activity; it was stimulated by 1.5–2‐fold in the presence of 0.001% Lubrol, Tween 20, poly(oxyethylene) 9‐lauryl ether and Nonidet P‐40, while 0.004% sodium lauryl sulfate inhibited the activity completely; concentrations of sodium molybdate and sodium vanadate necessary for 50% inhibition were 7 μM respectively; some proteins stimulated the activity, while lysophosphatidic acid, lysophosphatidylinositol, and phosphatidic acid suppressed the activity even in the presence of poly(oxyethylene) 9‐lauryl ether.