DEMONSTRATION OF A CD-COMPLEXING COMPOUND IN SCENEDESMUS-SUBSPICATUS AND ZEA-MAYS L SIMILAR TO PHYTOCHELATINS

Cells of the unicellular green algar Scenedesmus subspicatus which wer e cultivated in a Cd-treated nutrient solution under controlled condit ions for 24 h, produced a cytoplasmatic Cd-complexing compound with a molecular weight of 6,100 D. The Cd-compound was found to contain Cd-m ercaptid bondings and high levels of Cd and sulfhydryl groups. On the basis of the amino acid composition (43% glutainine acid, 36% cysteine , 11% glycine) and the reduction of synthesis by buthionine sulfoximin e, the Cd-compound was categorized as a phytochelatin. Maize grown in a Cd-containing nutrient solution reacted similarly by producing a Cd- complexing compound in roots. Synthesis of this compound was inhibited by buthionine sulfoximine completely. Therefore the Cd-compound found in the maize cells was considered to be a phytochelatin as well.