MOLECULAR DYNAMICS STUDIES ON MAMMALIAN APOMETALLOTHIONEINS

Despite innumerable publications on metallothionein (MT), the literature on apo-MT is limited. Without the understanding of apo-MT, it is not possible to study the metallation process of MT which is the key process involved in various functions of MT like metal transfer and heavy metal detoxification. The functional role of apo-MT is related to its structure. Considering the difficulty of spectroscopic measurements of apo-MT, the molecular dynamic (MD) simulations of mammalian apo-MTs i.e. human MT1a and MT2, rabbit MT1a and MT2a and rat MT1 and MT2 (individualanddomain as well as complete protein (i.e. connected ��)) in vacuum and water has been carried out using a linear strand of these proteins as starting geometry. The structural behavior of rat apo-MTs is different from that of human and rabbit apo-MTs. Both human apo-MTs and rabbit apo-MTs polypeptide backbone adopt an overall random coil structure except two small stretches of helix towards N-terminal after simulation in vacuum and water. Regardless of sequence homology of different mammalian MT isoforms, only the rat apo-MTs contain two stretches of helices towards the C-terminal. The extent of global folding of polypeptide backbone increases after 20 ns simulation in water that reduces its solvent exposed surface area.