Catalyzes the reversible transfer of high energy ATP gamma-phosphate group to L-arginine. ATP + L-arginine = ADP + H(+) + N(omega)-phospho-L-arginine Stable below pH 9.0. Degrades by incubation at pH 9.5 and 10.0 for 1 hour. Relatively stable below 30 degrees Celsius, but aggregates above 40 degrees Celsius. Flocculent precipitate appears by incubation at 70 degrees Celsius for 30 min. Muscle (at protein level). Causes an allergic reaction in human. Binds to IgE in 33% of the 12 patients tested allergic to octopus. IgE-binding activity can be significantly reduced with thermal, acidic or alkali treatment. Belongs to the ATP:guanido phosphotransferase family.