Adenylylsulfate Kinase Research Articles

Cysteine Biosynthesis in Salmonella typhimurium: the Presence of ATP-Sulfurylase and APS-Kinase in Various Cysteine-Requiring Mutants

Enzymatic tests were performed on a series of cysteine-requiring mutants for the presence of the sulfate activating enzymes. ATP-sulfurylase (sulfate adenylyltransferase EC 2.7.7.4) and APS-kinase (adenylylsulfate kinase EC 2.7.1.25). The enzymatic products adenosine 5'-[35S]sulfatophosphate and adenosine 3'-phosphate 5'-[35S]sulfatophosphate were identified by paper electrophoresis and measured quantitatively without elution from the paper. Cys mutants mapping in cistrons, A, H, I, J, G, and Ea contain both enzymes. Mutation in the D cistron leads to the loss of ATP-sulfurylase. Mutants mapping in the C cistron lack APS-kinase. Ba, Bb, and Bc mutants lack both enzymes. The control of the synthesis of these enzymes by cysteine was examined. Both enzymes are missing when cells are grown on cysteine.

Purification and properties of ATP-sulfurylase from furth mouse mastocytoma

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) 2SO 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.

Enzyme-substrate complexes of ATP-sulfurylase from mouse mastocytoma

1. 1.|A highly purified mouse mastocytoma ATP-sulfurylase (ATP: sulfate adenylyltransferase, EC 2.7.7.4) preparation was observed to bind ATP, when incubated with the triphosphate. Upon addition of inorganic sulfate to the enzyme-ATP complex, the enzyme-bound ATP was converted to enzyme-bound adenylylsulfate. 2. 2.|When the enzyme-adenylylsulfate complex was incubated in the presence of adenylylsulfate kinase and ATP, a partial conversion of the bound adenylylsulfate to free 3′-phosphoadenylylsulfate was noted. 3. 3.|On the basis of these results a reaction sequence was suggested for the mechanism of sulfate activation, with ATP-sulfurylase-ATP and ATP-sulfurylaseadenylylsulfate complexes as intermediates.

Lack of sulfate-activating enzymes in human breast tumors.

SummaryPreparations from human breast tumors which are inactive in the formation of steroid sulfates are shown to be lacking the two sulfate-activating enzymes, sulfate adenylyltransferase, and adenylylsulfate kinase, and to have measurable amounts of 3-β-hydroxysteroid sulfotransferase and estrone sulfotransferase. The study also suggests that the sulfate-activating enzymes are the limiting factor in determining the level of steroid conjugating activity of the tumor preparations that have the ability to form steroid sulfates.