Relationship between the Ligand Structure of Copper and the Stability of Superoxide Dismutase(Biological Chemistry)

概要

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The ligand structure of chelated copper in recombinant human Cu_2Zn_2SOD(r-hSOD) and its metal-substituted SODs was examined. In r-hSOD the configuration of the copper binding site was axially symmetrical and that of metal-substituted SODs had a tendency to change towards a tetrahedral type compared with r-hSOD except for Cu_2(VO)_2SOD. Cu_2(VO)_2SOD was not tetrahedral and in this case the ligand atom of copper was inclined to convert from nitrogen towards oxygen. In Cu_2E_2SOD, Ag_2Cu_2SOD, and Cu_2(VO)_2SOD the specific activities were lower but in Cu_2Cu_2SOD and Cu_2Co_2SOD they were nearly identical with that of r-hSOD. These results suggested the ligand structure of chelated copper was not related to the specific activity of SOD. However, these SODs were less stable than r-hSOD against heat treatment and denaturing reagent. Further they were less stable against attack by an inactivator (hydrogen peroxide) except for Cu_2(VO)_2SOD. In this case the decreased stability of these SODs was associated with the change of the ligand structure of copper from that of r-hSOD. These results suggested that the presence of zinc contributed highly to the stable formation of the ligand structure of copper and the enzymic stability.
社団法人日本農芸化学会の論文
1990-02-23