Sulfatase activity in the oyster Crassostrea virginica: Its potential interference with sulfotransferase determination

Two sulfatase isoforms, a soluble one with an optimum pH of 5.0, and a microsomal one with an optimum pH of 7.6, were observed in digestive gland, gonads, mantle and gills of the oyster C. virginica. The highest sulfatase activity was recorded in the digestive gland cytosol and is likely to interfere with the in vitro determination of sulfotransferase activity. Indeed, the sulfatase inhibitor Na2SO3 led to an increase of measured sulfotransferase activity (31 ± 9%), suggesting that those sulfatases might be partially responsible for the low sulfotransferase activities found in C. virginica.