Cysteinesulfinate decarboxylase activity as an index of taurine-containing structures.

The distribution of cysteinesulfinic acid decarboxylase (CSAD) activity has been studied for some time on the assumption that this activity was a marker for taurine-containing structures in the CNS. We have found that various in vivo and in vitro treatments of CNS tissues result in parallel changes in the activities of CSAD and glutamic acid decarboxylase (GAD). This suggests that the assay for CSAD is in fact measuring predominantly GAD activity. This hypothesis is tested by lesion, regional distribution, kinetic, inhibitor, and stability studies.