MEMORIES OF METALLOTHIONEIN

Metallothionein (MT) has provided nature with a small molecule which e xhibits multiple facets. The distinct arrangement of cysteine residues which occurs within the two domains of MT confers predisposed metal s pecificity upon each domain. Furthermore, subtle changes in primary se quence may be built onto the metal cluster scaffold. These not only be stow immunodistinction but may also potentially allow specific members of this family such as MT-III to fulfill unique biological roles. An understanding of how the structures of MT molecules predetermine their biochemical characteristics may allow the design of novel metal-bindi ng molecules specific for the metal ion of choice. Already, using natu re as a blueprint, a semi-specific cadmium-binding molecule has been c onstructed from a polymer of mammalian C-terminal domains. This novel protein has been used to protect tobacco plants from cadmium toxicity. In addition, modeling of biologically active determinants which are l ocated on the external face of MT-III may facilitate the design of sma ll synthetic molecules which mimick the biological activity of MT-III and prevent the distressing effects of memory and speech loss associat ed with Alzheimer's disease. Memories of metallothionein may yet be so mething worth remembering!