Phytochelatin

Phytochelatin

Chemical structure of phytochelatin

Phytochelatins are a family of peptides that play a crucial role in the detoxification of heavy metals in plants, fungi, and some bacteria. They are synthesized from glutathione and are characterized by the repeating unit (_-Glu-Cys)n-Gly, where n can vary from 2 to 11. Phytochelatins are important for the sequestration and detoxification of metals such as cadmium, lead, and mercury.

Biosynthesis

Phytochelatins are synthesized enzymatically from glutathione by the enzyme phytochelatin synthase. This process is activated in response to the presence of heavy metals. The enzyme catalyzes the transfer of a _-glutamylcysteine moiety from one glutathione molecule to another, forming the repeating units of phytochelatin.

Function

Phytochelatins bind to heavy metals through their thiol groups, forming stable complexes that are sequestered into the vacuole of plant cells. This sequestration prevents the metals from interacting with cellular components and causing damage. The ability of phytochelatins to chelate metals is crucial for the survival of plants in contaminated environments.

Role in Heavy Metal Tolerance

Plants exposed to heavy metals often exhibit increased levels of phytochelatins. This increase is part of the plant's adaptive response to metal stress. By binding and sequestering metals, phytochelatins reduce the toxic effects of metals on cellular processes, allowing plants to tolerate higher concentrations of metals.

Applications

Understanding the role of phytochelatins in metal detoxification has applications in bioremediation. Plants that produce high levels of phytochelatins can be used to clean up contaminated soils by absorbing and sequestering heavy metals. Genetic engineering approaches are also being explored to enhance phytochelatin production in plants, thereby increasing their capacity for metal detoxification.

Related pages

• Glutathione
• Heavy metal detoxification
• Bioremediation
• Cadmium