Chemical structure of phytochelatin. n = 2-11.

Phytochelatins are oligomers of glutathione, produced by the enzyme phytochelatin synthase. In Chemistry, an oligomer consists of a limited number of Monomer units (ολιγος or oligos is Greek for "a few" in contrast to a Glutathione ( GSH) is a Tripeptide. It contains an unusual Peptide linkage between the amine group of Cysteine and the Carboxyl They are found in plants, fungi, nematodes and all groups of algae including cyanobacteria. Plants are living Organisms belonging to the kingdom Plantae. A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ The nematodes or roundworms ( Phylum Nematoda from Greek (nema "thread" + -ode "like" are one of the most common Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy Phytochelatins act as chelators, and are important for heavy metal detoxification. Chelation is the binding or complexation of a bi- or multidentate Ligand. ^[1][2][3] They are abbreviated PC2 through PC11.

A mutant Arabidopsis thaliana lacking phytochelatin synthase is very sensitive to cadmium, but it grows just as well as the wild-type plant at normal concentrations of zinc and copper, two essential metal ions, indicating that phytochelatin is only involved in resistance to metal poisoning. Arabidopsis thaliana ( A-ra-bi-dóp-sis tha-li-á-na; thale cress, mouse-ear cress or Arabidopsis) is a small A mutant is an individual organism or new genetic character arising or resulting from an instance of Mutation, which is a base-pair sequence change within the DNA ^[4]

Because phytochelatin synthase uses glutathione with a blocked thiol group in the synthesis of phytochelatin, the presence of heavy metal ions that bind to glutathione causes the enzyme to work faster. In Organic chemistry, a thiol is a compound that contains the functional group composed of a Sulfur atom and a Hydrogen atom (-SH Therefore the amount of phytochelatin increases when the cell needs more phytochelatin to survive in an environment with high concentrations of metal ions. ^[5]

Phytochelatin seems to be transported into the vacuole of plants, so that the metal ions it carries are stored safely away from the proteins of the cytosol. In general vacuole functions include Removing unwanted structural debris Isolating materials that might be harmful or a threat to the cell Containing The cytosol or intracellular fluid (or cytoplasmic matrix) is the liquid found inside cells. ^[4]

Related peptides

There are groups of other peptides with a similar structure to phytochelatin, but where the last amino acid is not glycine:^[4][6]

History

Phytochelatin was first discovered in 1981 in fission yeast, and was named cadystin. Fabaceae or Leguminosae is a large and economically important family of Flowering plants which is commonly known as the legume family, pea Maize (ˈmeɪz ( Zea mays L. ssp mays) known as corn in some countries is a cereal grain domesticated in Mesoamerica Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described Poaceae or Gramineae is a family in the Class Liliopsida of the flowering plants. Maize (ˈmeɪz ( Zea mays L. ssp mays) known as corn in some countries is a cereal grain domesticated in Mesoamerica Horseradish ( Armoracia rusticana, syn Cochlearia armoracia) is a Perennial plant of the Brassicaceae family which also includes mustard Schizosaccharomyces pombe, also called "fission yeast" is a Species of Yeast. It was then found in higher plants in 1985 and was named phytochelatin. Vascular plants (also known as tracheophytes or higher plants) are those Plants that have lignified tissues for conducting In 1989 its enzyme, phytochelatin synthase, was discovered. ^[6]

References

1. ^ Suk-Bong Ha, Aaron P. Smith, Ross Howden, Wendy M. Dietrich, Sarah Bugg, Matthew J. O'Connell, Peter B. Goldsbrough, and Christopher S. Cobbett , Phytochelatin Synthase Genes from Arabidopsis and the Yeast Schizosaccharomyces pombe, Plant Cell, Vol. 11, 1153-1164, June 1999
2. ^ Olena K. Vatamaniuk, Elizabeth A. Bucher, James T. Ward and Philip A. Rea, A new pathway for heavy metal detoxification in animals: phytochelatin synthase is required for cadmium tolerance in Caenorhabditis elegans, The Journal of Biological Chemistry, April 2001
3. ^ InterPro database page on phytochelatin synthase
4. ^ ^{a b c} Buchanan, Gruissem, Jones, Biochemistry & molecular biology of plants, 1st edition, American Society of Plant Physiology, 2000
5. ^ O K Vatamaniuk, S Mari, Y Lu, and P A Rea, Mechanism of Heavy Metal Ion Activation of Phytochelatin (PC) Synthase, J. Biol. Chem. , Vol. 275, Issue 40, 31451-31459, October 6, 2000
6. ^ ^{a b} Masahiro Inouhe, Phytochelatins, Braz. J. Plant Physiol. vol. 17 no. 1 Londrina Jan. /Mar. 2005