Purification of a derepressible arylsulfatase from Chlamydomonas reinhardti: Properties of the enzyme in intact cells and in purified state

Abstract

Arylsulfatase (aryl-sulfate sulfohydrolase, EC 3.1.6.1) has been purified from SO 4 2−-starved cells of Chlamydomonas reinhardti. The enzyme ws isolated from acetone-powder extract by (NH 4) 2SO 4 precipitation, Sephadex G-200 filtration and ion-exchange chromatography. Only one fraction of aryl-sulfatase was found. The final preparation was homogenous by the criteria of sedimentation, diffusion and polyacrylamide gel electrophoresis. The purified enzyme had a molecular weight of about 150 000, estimated by ultracentrifugation and gel filtration, and an isoelectric point of 9.0. The properties of the enzyme as investigated in intact cells and in the purified state were found to be very similar except for the temperature optimum. Imidazole strongly increased the enzyme activity by increasing the V, but reduced the affinity for the substrate. The enzyme activity was competitively inhibited by borate with a greater affinity for borate than for the substrate. The Chlamydomonas enzyme is a Type I arylsulfatase since it was inhibited by CN −, but not by SO 4 2− and phosphate.