Purification and Properties of Adenosine-5’-Phosphosulfate Kinase from the Marine Red Macroalga Porphyra yezoensis Ueda

Adenosine-5′-phosphosulfate kinase (ATP: adenylylsulfate-3′-phosphotransferase, EC 2.7.1.25) was purified from the thalli of the marine alga Porphyra yezoensis by means of salt fractionation, affinity, gel filtration, and ion exchange chromatography. The native enzyme had a M_r of about 61000. Dissociation yielded a form of M_r about 31000. The maximum enzyme activity was at pH 7.0, and requires a divalent metal ion. Triphosphates of adenosine, cytidine, guanine, inosine, and uridine were active as the phosphate donor substrate. Adenosine-5′-phosphosulfate exhibited potent substrate inhibition; the optimal concentration was 3.0 μM in the presence of excess ATP and Mg²⁺. Michaelis constants for APS and ATP were 0.45 μM and 0.46 mM, respectively.