The effects of nano-anatase TiO(2) on the activation of lactate dehydrogenase from rat heart.
Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO(2) was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which TiO(2) exerts its toxicity has not been completely understood. In this report, we investigated the mechanisms of nano-anatase TiO(2) (5 nm) on LDH activity in vitro. Our results showed that LDH activity was greatly increased by low concentration of nano-anatase TiO(2), while it was decreased by high concentration of nano-anatase TiO(2). The spectroscopic assays revealed that the nano-anatase TiO(2) particles were directly bound to LDH with mole ratio of [nano-anatase TiO(2)] to [LDH] was 0.12, indicating that each Ti atom was coordinated with five oxygen/nitrogen atoms and a sulfur atoms of amino acid residues with the Ti-O(N) and Ti-S bond lengths of 1.79 and 2.41 A. We postulated that the bound nano-anatase TiO(2) altered the secondary structure of LDH, created a new metal ion-active site for LDH, and thereby enhanced LDH activity.
Duan
Yanmei
Y
Medical College of Soochow University, Suzhou, People's Republic of China.
Liu
Huiting
H
Zhao
Jinfang
J
Liu
Chao
C
Li
Zhongrui
Z
Yan
Jinying
J
Ma
Linglan
L
Liu
Jie
J
Xie
Yaning
Y
Ruan
Jie
J
Hong
Fashui
F
D000818:Animals; D004396:Coloring Agents / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis* / Q000737:chemistry / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology*; D053758:Nanoparticles / Q000633:toxicity*; D051381:Rats; D014025:Titanium / Q000633:toxicity*
D004396:Coloring Agents; C009495:titanium dioxide; D014025:Titanium; D007770:L-Lactate Dehydrogenase