Effects of Eu3+ on the metabolism of amino acid and protein in xerophytic Lathyrus sativus L.

The contents of amino acids and proteins and the activity of Na+,K+-ATPase were determined in roots, stems, and leaves of Eu3+-treated Lathyrus sativus L. The results showed that the treatment of Eu3+ made the contents of amino acid and protein and the activity of Na+,K+-ATPase change. The first possible mechanism was that Eu3+ directly made the electric potential of -NH2 or -COOH of amino acid change. The second possible mechanism was that Eu3+ played a role in metallic-activated factors of certain enzymes, which catalyze the catabolism and anabolism of protein. Then, the contents of amino acids and proteins were relatively changed. The third possible mechanism was that Eu3+ regulated the activity of ATPase through changing the Na+/K+ ratio. The energy released by ATPase was the driving force for the translocation of amino acids and proteins in the plant cell. Because of the changeability of its valence, Eu3+ played an important role in regulating certain physiological reactions to increase the adaptability of L. sativus in arid environment.