Figure 1.
Chemical structures of four catechins: (A) EC, (B) EGC, (C) ECG, and (D) EGCG.
Figure 2.
The fluorescence emission spectra of native catalase (5×10−7 M) and the quenching effect of catechins on its fluorescence intensity at 25°C (λex = 280 nm): (A) EC-catalase, (B) EGC-catalase, (C) ECG-catalase, and (D) EGCG-catalase.
Curves (1 to 8) denote 2.5×10−9 M to 1.7×10−8 M of catechins.
Figure 3.
Double logarithmic plot of catalase-catechins system at 25°C (λex = 280 nm).
(A) EC-catalase, (B) EGC-catalase, (C) ECG-catalase, and (D) EGCG-catalase.
Figure 4.
ITC profiles for catalase (1 µM) when titrated with catechins (10 µM each) at 25°C: (A) EC-catalase, (B) EGC-catalase, (C) ECG-catalase, and (D) EGCG-catalase systems.
Table 1.
Thermodynamic parameters from ITC experiments for catalase-catechins system at 25°C.
Figure 5.
The CD spectra of catalase (1 µM) and its complexes with catechins and 3-AT (3 µM each) at 25°C.
The curves (a to f) represent pure catalase, EGC-catalase, EC-catalase, ECG-catalase, EGCG-catalase, and 3-AT-catalase complexes, respectively.
Figure 6.
Decay curves of H2O2 by pure catalase (A) and by cellular catalase (B) in absence (□) and presence of EGC (▪), EC (•), ECG (▴), EGCG (*), 3-AT (▾) as recorded by spectrophotometer at 240 nm. Initial H2O2 concentration was approximately 0.01 mM.
Figure 7.
Double reciprocal plot or Lineweaver-Burk plot of catalase – H2O2 (▪) and catalase+EGCG – H2O2 (*) reactions.
Figure 8.
Histograms representing the intracellular ROS content in absence and presence of various concentrations (12.5–100 µM) of EGCG.
(*p<0.05 as compared to control group).