Battistoni A, Folcarelli S, Gabbianelli R, Capo C, Rotilio G
Department of Biology, University of Rome Tor Vergata, Italy.
Biochem J. 1996 Dec 15;320 ( Pt 3)(Pt 3):713-6. doi: 10.1042/bj3200713.
Gel-filtration chromatography experiments performed at high protein concentrations demonstrate that the Cu,Zn superoxide dismutase from Escherichia coli is monomeric irrespective of the buffer and of ionic strength. The catalytic activity of the recombinant enzyme is comparable with that of eukaryotic isoenzymes, indicating that the dimeric structure commonly found in Cu,Zn superoxide dismutases is not necessary to ensure efficient catalysis. The analysis of the amino acid sequences suggests that an altered interaction between subunits occurs in all bacterial Cu,Zn superoxide dismutases. The substitution of hydrophobic residues with charged ones at positions located at the dimer interface of all known Cu,Zn superoxide dismutases could be specifically responsible for the monomeric structure of the E. coli enzyme.
在高蛋白浓度下进行的凝胶过滤色谱实验表明，来自大肠杆菌的铜锌超氧化物歧化酶是单体，与缓冲液和离子强度无关。重组酶的催化活性与真核同工酶相当，这表明铜锌超氧化物歧化酶中常见的二聚体结构对于确保高效催化并非必需。氨基酸序列分析表明，所有细菌铜锌超氧化物歧化酶中亚基间的相互作用都发生了改变。在所有已知铜锌超氧化物歧化酶二聚体界面处的位置用带电荷的残基取代疏水残基可能是大肠杆菌酶单体结构的具体原因。
