Galiazzo F, Ciriolo M R, Carrì M T, Civitareale P, Marcocci L, Marmocchi F, Rotilio G
Department of Biology, Tor Vergata University, Rome, Italy.
Eur J Biochem. 1991 Mar 28;196(3):545-9. doi: 10.1111/j.1432-1033.1991.tb15848.x.
The Cu/Zn superoxide dismutase activity of Saccharomyces cerevisiae was found to be strictly related to the extent of oxygen metabolism, since cells grown under anaerobic or repressed conditions were found to contain 10% and 40% the activity of derepressed cells, respectively. The dependence of Cu/Zn superoxide dismutase on oxygen was found to be related to the availability of copper to the cells since the enzyme activity and immunoreactive protein measured under the various conditions was roughly proportional to the copper content of cells and in anaerobic cells a large fraction of the enzyme was found to be in the form of an inactive proenzyme which was activated by the addition of copper to cell extracts. The Cu/Zn superoxide dismutase mRNA did not parallel the dependence of the enzyme concentration on oxygen metabolism, suggesting that the gene expression was affected by copper also at the post-transcriptional level. However, under conditions of copper overloading, a more direct effect on transcription was observed and the presence of the inactive proenzyme in anaerobic cultures was associated with the over-expression of metallothionein.
酿酒酵母的铜锌超氧化物歧化酶活性被发现与氧代谢程度密切相关，因为在厌氧或受抑制条件下生长的细胞分别含有去抑制细胞活性的10%和40%。铜锌超氧化物歧化酶对氧的依赖性被发现与细胞对铜的可利用性有关，因为在各种条件下测得的酶活性和免疫反应性蛋白大致与细胞的铜含量成正比，并且在厌氧细胞中发现大部分酶以无活性的酶原形式存在，通过向细胞提取物中添加铜可使其激活。铜锌超氧化物歧化酶mRNA与酶浓度对氧代谢的依赖性并不平行，这表明基因表达在转录后水平也受铜的影响。然而，在铜过载条件下，观察到对转录有更直接的影响，并且厌氧培养物中无活性酶原的存在与金属硫蛋白过度表达有关。
