Petersen Steen V, Oury Tim D, Ostergaard Louise, Valnickova Zuzana, Wegrzyn Joanna, Thøgersen Ida B, Jacobsen Christian, Bowler Russell P, Fattman Cheryl L, Crapo James D, Enghild Jan J
Departments of Molecular Biology and Medical Biochemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
J Biol Chem. 2004 Apr 2;279(14):13705-10. doi: 10.1074/jbc.M310217200. Epub 2004 Jan 21.
The antioxidant enzyme extracellular superoxide dismutase (EC-SOD) is mainly found in the extracellular matrix of tissues. EC-SOD participates in the detoxification of reactive oxygen species by catalyzing the dismutation of superoxide radicals. The tissue distribution of the enzyme is particularly important because of the reactive nature of its substrate, and it is likely essential that EC-SOD is positioned at the site of superoxide production to prevent adventitious oxidation. EC-SOD contains a C-terminal heparin-binding region thought to be important for modulating its distribution in the extracellular matrix. This paper demonstrates that, in addition to binding heparin, EC-SOD specifically binds to type I collagen with a dissociation constant (K(d)) of 200 nm. The heparin-binding region was found to mediate the interaction with collagen. Notably, the bound EC-SOD significantly protects type I collagen from oxidative fragmentation. This expands the known repertoire of EC-SOD binding partners and may play an important physiological role in preventing oxidative fragmentation of collagen during oxidative stress.
抗氧化酶细胞外超氧化物歧化酶（EC-SOD）主要存在于组织的细胞外基质中。EC-SOD通过催化超氧阴离子自由基的歧化反应参与活性氧的解毒过程。由于其底物具有反应活性，该酶的组织分布尤为重要，并且EC-SOD定位在超氧产生的部位以防止意外氧化可能是必不可少的。EC-SOD含有一个C端肝素结合区域，该区域被认为对调节其在细胞外基质中的分布很重要。本文证明，除了结合肝素外，EC-SOD还以200 nM的解离常数（K(d)）特异性结合I型胶原。发现肝素结合区域介导了与胶原的相互作用。值得注意的是，结合的EC-SOD能显著保护I型胶原免受氧化断裂。这扩展了已知的EC-SOD结合伙伴库，并且可能在预防氧化应激期间胶原的氧化断裂中发挥重要的生理作用。
