부산대학교 도서관

Evidence for the presence of the metal-binding protein metallothionein, MT, in higher plants is equivocal. Although a number of MT-Like metal complexes have been isolated from plants, the chemical structures of most of these compounds have not been fully elucidated. Recently a novel class of plant peptides, poly (γ-glutamylcysteinyl)glycines, (γEC)nG, have been discovered. These peptides bind metal ions, and in the presence of such ions the amount of (γEC)nG in plant cells increases. The presence of peptide bonds through the γ-carboxyl group of glutamate, rather than the α- carboxyl group, suggests that these peptides are not encoded by structural genes but are the products of biosynthetic pathways. Cells which are resistant to supra-optimal concentrations of certain metal ions over-produce (γEC)nG. ((γEC)nG may be functional analogues of MT. Whether or not some plants also produce MT is an important question which remains to be answered. [ABSTRACT FROM AUTHOR]