Purification and properties of ATP-sulfurylase from Furth mouse mastocytoma.

Abstract 1. 1.|The enzyme, ATP-sulfurylase (ATP:sulfate adenylyltransferase, EC 2.7.7.4) which catalyzes the reaction, ATP + inorganic sulfate ⇌ adenylyl sulfate + inorganic pyrophosphate, was purified from a high-speed supernatant of mouse mastocytoma (Furth) by (NH 4 ) 2 SO 4 fractionation, hydroxylapatite column chromatography, and Geon resin electrophoresis. The purification resulted in a 545-fold increase in specific activity. 2. 2.|The purified enzyme exhibited a pH optimum of 8.5, and it was free of inorganic pyrophosphatase (EC 3.6.1.1), ATP phosphohydrolase (EC 3.6.1.3), adenylylsulfate kinase (EC 2.7.1.25) and adenylylsulfate sulfohydrolase. 3. 3.|The enzyme did not show an absolute requirement for metal ions, but its activity was increased by Mn 2+ , Mg 2+ , and Zn 2+ . EDTA was a powerful inhibitor of the ATP-sulfurylase; this inhibition was reversed by Mn 2+ , Mg 2+ , Cu 2+ , Co 2+ and Zn 2+ . 2 mM solution of Ni 2+ , Ba 2+ and Ca 2+ inhibited the enzyme. 4. 4.|The enzyme reacted only with adenylylsulfate or deoxyadenylylsulfate and inorganic pyrophosphate as substrates (ATP sulfurylase reaction in reverse). Nucleotidylsulfates other than adenylylsulfate inhibited the reaction, when added to the latter as substrate. 5. 5.|The reaction catalyzed by the mastocytoma ATP-sulfurylase exhibited saturation phenomena, but it did not strictly follow Michaelis-Menten kinetics.