Phytochelatins are the most important heavy metal binding and heavy metal detoxifying peptides in plants. The formation of these peptides upon addition of different metals and metalloids was studied in plant cell cultures and in seedlings of Arabidopsis thaliana. Cadmium, lead, mercury, copper, tin, iron, chromium and molybdenum, arsenic, antimony and bismuth induced the formation of phytochelatins in plant cell cultures; selenium, vanadium and cobalt did not, however. By gel filtration the existence of phytochelatin complexes of lead, mercury and antimony could be demonstrated. Upon addition of arsenite or arsenate a dramatic increase of phytochelatins could be observed. The identity of the formed peptides was confirmed by mass spectrometry (ESI-MS). The existence of an in vivo formed complex between arsenic and phytochelatins could be demonstrated by gel filtration under optimized conditions. The mass spectrometrical analysis of a synthesized complex showed the expected stoichiometry of three SH groups per As. With the yeast two hybrid system the question was studied, if the phytochelatin synthase is active as an homodimer of two approximately 50 kDa subunits. The yeasts transformed with the phytochelatin synthase gene from Arabidopsis thaliana showed phytochelatin formation upon Cd2+ addition; however, the phytochelatin synthase is not active as an homodimer, as the interaction in the yeast two hybrid system could not be observed.
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Phytochelatins are the most important heavy metal binding and heavy metal detoxifying peptides in plants. The formation of these peptides upon addition of different metals and metalloids was studied in plant cell cultures and in seedlings of Arabidopsis thaliana. Cadmium, lead, mercury, copper, tin, iron, chromium and molybdenum, arsenic, antimony and bismuth induced the formation of phytochelatins in plant cell cultures; selenium, vanadium and cobalt did not, however. By gel filtration the exi...
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