Structure studies of platinothioneins by using extended X-ray absorption fine structure spectroscopy

The metal binding sites in the two Pr containing metallothioneins (Pt7MT an d Pt14MT) were examined by means of Pt(II) L-3-edge extended X-ray absorpti on finestructure (EXAFS) spectroscopy. Comparisons between the phase and am plitude functions derived from the isolated shells to those of Pt...Pt, Pt- S and Pt-N model components showed that each platinum in Pt7MT was; coordin ated by four sulfur atoms at a distance of 2.31+/-0.01 Angstrom. Analysis o f the outer shell data of platinum atom in Pt7MT indicated backscattering p latinum atom at approximate 4.29 Angstrom. Strikingly different structural parameters had been obtained for the Pt14MT species, fitting of the first s hell revealed that each platinum was coordinated by two sulfurs at the dist ance of 2.30+/-0.02 Angstrom and two nitrogens at 2.02+/-0.02 Angstrom. The results of the work provided the detailed information concerning the local environments of the coordinated Pt(II) in these two platinothioneins.