Reconstitution of stellacyanin as a case of direct Cu(I) transfer between yeast copper thionein and 'blue' copper apoprotein.

It was of interest to examine whether yeast Cu-thionein could be used to transfer the thiolate bound copper directly into the copper binding site of 'blue' apoproteins which contain free thiol groups. In particular apo-stellacyanin was used in the present study and it was found to be able to accept Cu(I) from yeast Cu-thionein, without any detectable unspecific Cu(II) intermediate, both aerobically and anaerobically.