Du Nana, Sheng Liangquan, Liu Zhaodi, Hu Xiaojuan, Xu Huajie, Chen Shuisheng
College of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041, People's Republic of China.
College of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041, People's Republic of China ; College of Chemistry and Chemical Engineering, Anhui University, Hefei 230039, People's Republic of China.
Chem Cent J. 2013 Jun 6;7:97. doi: 10.1186/1752-153X-7-97. eCollection 2013.
Isoniazid (INH) is front-line anti-tuberculosis (TB) drugs, which are usually prescribed to TB patients for a total period of 6 months. Antituberculosis drug-induced hepatotoxicity (ATDH) is a serious adverse reaction of TB treatment. It is reported that INH-induced hepatotoxicity is associated with oxidative stress. Superoxide dismutase (SOD, EC 1.15.1.1) is the key enzyme for the protection of oxidative stress, which catalyzes the removal of superoxide radical anion, thereby raising the need to better understand the interaction between INH and SOD.
The experimental results showed that the fluorescence intensity of Cu/Zn-SOD regularly decreased owing to form a 1:1 INH-SOD complex. According to the corresponding association constants (K SV) between INH and SOD obtained from Stern-Volmer plot, it is shown that values of K A are 1.01 × 10(4), 5.31 × 10(3), 3.33 × 10(3), 2.20 × 10(3) L · mol(-1) at four different temperatures, respectively. The binding constants, binding sites and the corresponding thermodynamic parameters ((Δ) H, (Δ) G and (Δ) S) were calculated. A value of 3.93 nm for the average distance between INH and chromophore of Cu/Zn-SOD was derived from Förster theory of non-radiation energy transfer. The conformational investigation showed that the presence of INH resulted in the microenvironment and conformational changes of Cu/Zn-SOD. In addition, Effects of INH on superoxide dismutase activity was examined.
The results show that the hydrogen bonding and van der Waals forces play major roles in stabilizing the 1:1 INH-SOD complex. After addition of INH during the range of the experiment, the conformation and microenvironment of Cu/Zn-SOD are changed, but the activity of Cu/Zn-SOD is not changed.
异烟肼（INH）是一线抗结核药物，通常给结核病患者开的疗程为6个月。抗结核药物性肝毒性（ATDH）是结核病治疗的一种严重不良反应。据报道，异烟肼诱导的肝毒性与氧化应激有关。超氧化物歧化酶（SOD，EC 1.15.1.1）是保护氧化应激的关键酶，它催化超氧阴离子自由基的清除，因此有必要更好地了解异烟肼与SOD之间的相互作用。
实验结果表明，由于形成了1:1的INH-SOD复合物，Cu/Zn-SOD的荧光强度有规律地降低。根据从Stern-Volmer图获得的异烟肼与SOD之间的相应缔合常数（KSV），结果表明在四个不同温度下KA值分别为1.01×10(4)、5.31×10(3)、3.33×10(3)、2.20×10(3) L·mol(-1)。计算了结合常数、结合位点及相应的热力学参数（ΔH、ΔG和ΔS）。根据Förster非辐射能量转移理论得出异烟肼与Cu/Zn-SOD发色团之间的平均距离为3.93 nm。构象研究表明，异烟肼的存在导致了Cu/Zn-SOD的微环境和构象变化。此外，还检测了异烟肼对超氧化物歧化酶活性的影响。
结果表明，氢键和范德华力在稳定1:1的INH-SOD复合物中起主要作用。在实验范围内加入异烟肼后，Cu/Zn-SOD的构象和微环境发生了变化，但Cu/Zn-SOD的活性没有改变。
