Premium
The role of Cu(I)‐thiolate clusters during the proteolysis of Cu‐thionein
Author(s) -
Weser Ulrich,
Mutter Wolfgang,
Hartmann Hans-Jürgen
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80338-6
Subject(s) - proteolysis , chemistry , biophysics , biochemistry , biology , enzyme
Rat liver Cu,Zn‐[ 35 S]thionein and yeast Cu‐thionein were subjected to proteolysis in vitro using equilibrium dialysis. The partially copper‐loaded vertebrate thionein (2–7 ) was affected by different proteases including thermolysin, proteinase K, protease from Streptomyces griseus and lysosomal enzymes. Unlike the 2Cu‐thionein the respective 7Cu‐thiolate‐centred metallothionein was hardly proteolytically digested. In contrast to fully copper‐loaded native yeast Cu‐thionein both the H 2 O 2 ‐oxidized and the metal‐free protein were effectively cleaved in the presence of proteinase K. It is important to realize that the native Cu(I)‐thiolate chromophore survives the proteolytic attack. When the copper‐sulphur bonding is broken and the same amount of copper is unspecifically bound to the thionein portion, proteolysis proceeds identically with respect to the rate observed in the presence of the apoprotein. The unsuccessful proteolysis of native Cu‐thionein is not attributable to a simple copper‐dependent inhibition of the proteinases. It is suggested that prior to proteolysis the copper‐sulphur clusters must be destroyed.