Regulation of Adenosine 5′-Phosphosulfate Sulfotransferase in Higher Plants

APSSTAse catalyses the transfer of the sulfonylgroup of APS to a carrier (car-SH) to form car-S-SO 3 - . The carrier seems to be reduced glutathione in Chlorella (Tsang and Schiff, 1978). Using mutants blocked for sulfate reduction, APSSTase has been shown to be an enzyme of assimilatory sulfate reduction in Chlorella (Schmidt et al., 1974). The regulatory properties of the enzyme presented in this paper, together with enzymatic analysis (Schmidt, 1976), indicate that it is also involved in assimilatory sulfate reduction of higher plants. APSSTase has been detected in more than 50 families of higher plants (Schmidt, 1975a) and has been partially purified from spinach (Schmidt, 1976).