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Ma L, Ze Y, Liu J, Liu H, Liu C, Li Z, Zhao J, Yan J, Duan Y, Xie Y, Hong F: Direct evidence for interaction between nano-anatase and superoxide dismutase from rat erythrocytes. Spectrochim Acta A Mol Biomol Spectrosc. 2009 Jul 15;73(2):330-5. Epub 2009 Mar 6.
Nano-TiO2 and superoxide dismutase (SOD, EC 1.15.1.1) have been added to cosmetics and used to prevent injury of skin from UV-radiation, which might be related to the decrease of oxidative damage of skin. In previous studies we had proven that nano-anatase could increase the activity of SOD and decrease the oxidative damage in vivo. The mechanisms by which nano-anatase promoted SOD activity, however, are still not clearly understood. In the present work, nano-anatase in various concentrations was added to SOD from rat erythrocytes in vitro to gain insight into the mechanism of molecular interactions between nano-anatase and SOD by various spectral methods, suggesting that the reaction between SOD and nano-anatase was two-order, which meant that the SOD activity was greatly increased by low concentration of nano-anatase and inhibited by high concentration of nano-anatase. The spectroscopic assays suggested that the nano-anatase was determined to directly bind to SOD; the binding site of nano-anatase to SOD was 0.256 and the binding constants were 6.54 x 10 (5) and 3.6 x 10 (5) Lmol (-1); Ti was bound with three oxygen or nitrogen atoms and a sulfur atoms of amino acid residues at the Ti-O (N) and Ti-S bond lengths of 1.86 and 2.37 A, respectively, the binding nano-anatase entirely altered the secondary structure of SOD. It implied that the nano-anatase coordination created a new metal ion-active site form in SOD, thus leading to an enhancement in SOD activity. |
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