MOSSBAUER STUDIES ON IRON(II)-SUBSTITUTED YEAST METALLOTHIONEIN

Iron(II)-substituted yeast metallothionein has been studied with Mossb auer spectroscopy. The iron in the protein is in the high-spin ferrous state. A maximum metal content of four iron(II)/ molecule has been de termined, with the four metal ions forming a diamagnetic cluster due t o the antiferromagnetic exchange interaction between Fe2+ via bridging thiolates. In the case where the iron titration gives a value of less than four iron(II)/apoprotein, the metal ions are magnetically nonint eracting, with each individual iron(II) behaving like iron(LT) in redu ced rubredoxin.