Phytochelatins

Grill, E., Winnacker, E.-L. Zenk, M.H. (1985). Phytochelatins The principal heavy-metal complexing peptides of higher plants. Science, 230, 674-6. 

Stillman, M.J. Shaw, C.F. Jill and Suzuki, K.T (eds) (1992) MetaUothioneins Synthesis, Structure, and Properties of MetaUothioneins, Phytochelatins and Metal-... 

Robbins, A.H. and Stout, C.D. (1992) Metallothioneins Synthesis, Structure and Properhes of Metallothioneins, Phytochelatins, and Metal-Thiolate Complexes (eds M.l. ShDman, C.F. Shawlll and KT. Suzuki), VCH Publishers, Weinheim, pp. 31—54. 

Gawel JE, Trick CG, Morel FM. 2001. Phytochelatins are bioindicators of atmospheric metal exposure via direct foliar uptake in trees near Sudbury, Ontario, Canada. Environ Sci Technol 35 2108-2113. 

Nickel is localized predominantly in the epidermal and subepidermal of the leaves. However, in leaves of some hyperaccumulator plants such as T. caerulescens and T. goesingense, Ni and Zn are found mainly in vacuoles (Salt and Kramer, 2000). Trace elements also are inactivated in the vacuoles as high-affinity low-molecular-weight metal chelators (such as Cd-phytochelatin complex), providing plants with trace element tolerance. Some Ni in leaves is found to be associated with cell wall pectates as well. 

Metallothioneins, Phytochelatins, Siderophores, Porphyrins 1-2 Low Very strong ... 

Cobbett C. S., 2000, Phytochelatins and their role in heavy metal detoxification, Plant Physiol. 123 825-832. 

Goldsbrough P., 2000, Metal tolerance in plants The role of phytochelatins and metallothioneins, in Phytoremediation of contaminated soil and water, N. Terry, G. Banuelos, eds, Lewis Publishers, Boca Raton. 

The metabolism of sulphur plays an important role in metal response, since most chelators, including metallothioneins and phytochelatins, contain this element. APSl encodes an ATP sulfurylase and Brassica juncea has been engineered to constitutively express this gene (Pilon-Smits et al., 1999). The plants showed increased S assimilation, higher glutathione (GSH) levels and were more tolerant to Se, accumulating 2-fold higher Se levels in the shoots. 

Lee, S., Moon, J. S., Ko, T.-S., Petros, D., Goldsbrough, P. B., and Korhan, S. S., 2003b, Overexpression of Arabidopsis phytochelatin synthase paradoxically leads to hypersensitivity to cadmium stress, Plant Physiol. 131 656-663. 

Schmoger MEV, Oven M, Grill E. 2000. Detoxification of arsenic by phytochelatins in plants. Plant Physiology 122 793-801. 

Within a relatively short period the purification of these metal-binding components had been completed by several groups (Grill et al., 1985 Steffens et al., 1986 Reese Wagner, 1987 Jackson et al., 1987). Unfortunately, this led to a series of different names for the same molecules (see Steffens, 1990) for clarity in this chapter, we are using the term phytochelatin as a contrast to gene-encoded MTs. 

In contrast to MT induction, the available evidence suggests that PC synthesis is not stimulated by direct transcriptional activation. PCs can be synthesised very rapidly (within 5 min) in response to metals entering the cells, even when protein synthesis is totally inhibited (Scheller et al., 1987 Robinson etal., 1988). Phytochelatin synthase thus appears to be a constitutive enzyme. Loeffler et al. (1989) have shown that, for the enzyme purified from Silene cucubalus, metal ion induction is a post-... 

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