Direct evidence for interaction between nano-anatase and superoxide dismutase from rat erythrocytes.
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.
Ma
Linglan
L
Medical College of Soochow University, Suzhou 215123, China.
Ze
Yuguang
Y
Liu
Jie
J
Liu
Huiting
H
Liu
Chao
C
Li
Zhongrui
Z
Zhao
Jinfang
J
Yan
Jinying
J
Duan
Yanmei
Y
Xie
Yaning
Y
Hong
Fashui
F
D000818:Animals; D004912:Erythrocytes / Q000201:enzymology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051379:Mice; D049329:Nanostructures / Q000737:chemistry*; D017433:Protein Structure, Secondary; D051381:Rats; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism*; D014025:Titanium / Q000737:chemistry*
D016166:Free Radical Scavengers; C009495:titanium dioxide; D014025:Titanium; D013482:Superoxide Dismutase