Regulation of adenosine 5?-phosphosulfate sulfotransferase activity by H2S and cyst(e)ine in primary leaves of Phaseolus vulgaris L.

Abstract
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.