REGULATION OF SULFATE ASSIMILATION IN PLANTS .8. REGULATION OF ADENOSINE 5'-PHOSPHOSULFATE SULFOTRANSFERASE ACTIVITY BY H2S AND CYST(E)INE IN PRIMARY LEAVES OF PHASEOLUS-VULGARIS L

During chloroplast development in the primary leaves of Phaseolus vulgaris, the extractable activity of adenosine 5′-phosphosulfate sulfotransferase increased ten-fold. When chloroplast development took place in air enriched with 3.5 μl H2S·l-1 there was a decrease in adenosine 5′-phosphosulfate sulfotransferase activity. Cyst(e)ine in concentrations up to 1 mM (in the external medium) did not affect the increase in adenosine 5′-phosphosulfate sulfotransferase activity in intact plants. In plants with excised roots, 0.75 mM cyst(e)ine inhibited this increase. In green primary leaves, H2S or cyst(e)ine treatment resulted in a decrease of extractable adenosine 5′-phosphosulfate sulfotransferase activity. In intact plants, this effect of cyst(e)ine was observed at a concentration of 1 mM, and in plants with excised roots, 0.25 mM had a comparable effect. In developing plants, the extractable activities of O-acetyl-L-serine sulfhydrylase (EC 4.2.99.9) and ribulosebisphosphate carboxylase (EC 4.1.1.39.) were not affected by H2S or cyst(e)ine. © 1979 Springer-Verlag.