THE ASSOCIATION OF METALLOTHIONEIN WITH PHOSPHATE

Dose-dependent binding of inorganic phosphate to pre-irradiated metall othionein (MT) was observed by gel-filtration using sodium [P-32]phosp hate, whereas no association of phosphate with the natural MT can be o bserved. The circular dichroism (CD) spectra indicate that after irrad iation, some terminal thiolate ligands in MT are transformed to bridgi ng ones, and some destroyed, which results in unsaturated coordination of metal ions. Accordingly, it is reasonable to assume that in irradi ated MT, nonsulfur ligands, e.g. oxygen in Pi, take part in metal coor dinations, which leads to the interactions of MT with Pi.