Chemical tools for biological investigations of carbohydrate sulfotransferases—a class of enzymes that has been characterized only recently—have been developed by using a small‐molecule library‐screening approach. The inhibitor screen included 139 compounds comprising selected structures from purine libraries as well as commercially available protein‐kinase inhibitors and representatives from other kinase‐inhibitor families. Like kinases, carbohydrate sulfotransferases have attracted significant interest because of their roles in a variety of disease states including chronic inflammation and tumor metastasis.

We thank Sharon Long and Dave Keating for providing both the NodH sulfotransferase and APS Kinase during our preliminary experiments and Jack Kirsch for numerous helpful conversations. J.I.A. and K.G.B were supported by NIH Molecular Biophysics Training Grant (No. T32GM0895). This research was funded by grants to C.R.B. from the Pew Scholars Program, the W. M. Keck Foundation and the American Cancer Society (Grant No. RPG9700501BE).