The binding characteristics of isoniazid with copper–zinc superoxide dismutase and its effect on enzymatic activity

Abstract

BackgroundIsoniazid (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.ResultsThe 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 (KSV) between INH and SOD obtained from Stern–Volmer plot, it is shown that values of KA are 1.01 × 104, 5.31 × 103, 3.33 × 103, 2.20 × 103 L · mol−1 at four different temperatures, respectively. The binding constants, binding sites and the corresponding thermodynamic parameters (ΔH, ΔG and ΔS) 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.ConclusionsThe 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.

Physicochemical properties of polysaccharides from Dendrobium officinale by fractional precipitation and their preliminary antioxidant and anti-HepG2 cells activities in vitro

“…O 2 − scavenging activities of DOP-40, DOP-50, DOP-60, and DOP-70 were evaluated by pyrogallol autoxidation method, with slight innovation [24]. Four sample solutions were diluted with Tris–HCl buffer (0.05 mol/l, pH 7.4) to form various mixed solutions (0.5 mg/ml, 1 mg/ml, 2 mg/ml, 3 mg/ml, and 5 mg/ml), and then 0.4 ml of pyrogallic acid (60 mM) was added to the mixture solutions at 25 °C.…”

Pharmacogenetics of isoniazid-induced hepatotoxicity

“…Besides the mechanism of G6PD as antioxidant, SOD, also has antioxidant activity by catalyzing the conversion of superoxide radical anions to hydrogen peroxide (H 2 O 2 ) (Du et al, 2013). H 2 O 2 is a strong oxidizing agent that can cause oxidative damage and generate ROS.…”

“…A role of GST is to detoxify the toxic metabolites (Metushi et al, 2011;Roy et al, 2008). To date, the role of human leukocyte antigen (HLA) and superoxide dismutase (SOD) in the isoniazid metabolism is still being explored (Boelsterli & Lee, 2014;Du et al, 2013). Some genetic variants could interfere with the activity of the enzymes.…”