摘要
随着科技的发展,农业生产大量使用各种各样的除真菌剂、除害虫剂和消毒剂。另外,工业生产所排放的废水、废气均对整个生态环境造成不同程度的污染,其中尤以重金属的污染为甚。过量的重金属离子如锌、铜、镉等对生物体具有毒性,它们甚至能通过食物链进入人体而引起多种疾病。在高等植物中,重金属的毒性主要表现在以下几个方面:(1)抑制植物水分的吸收和运输;(2)抑制光合作用;(3)抑制呼吸作用;(4)抑制其它新陈代谢。这些抑制作用,最终导致植物萎黄、褪色、枯死。
Heavy metal binding complexes found in the cytoplasm of plant cells are widely reported to be responsible for metal resistance. It is believed that these metal binding complexes may play an important role in the accumulation of heavy metal and preventing them from enter- ing the plant metabolic pathways. This review summarizes information on purification, cha- racterization and properties of these molecules. In view of their inducibility, low molecular weight, specific optical characteristics (high absorption at 254nm and low absorption at 280 nm), high cysteine content and high capacity for binding heavy metal, these complexes were once proposed to be metallothionein-like molecules. However differing from metallothionein of animal system, heavy metal binding complexes in plants are comprised mainly of three amino acids with a unique structure of (γ-Glu-Cys)n-Gly ((γ-EC)_nG) (n=2--11). With the presence of γ-carboxyl group peptide linkage, the complexes are thought not to be synthesized via mRNA but the product of biosynthetic pathway using glutathione as precursor.
关键词
植物
重金属结合体
重金属耐性
Phytochelatins
Heavy metal binding peptides
Heavy metal tolerance
