Skip to main content
. 2022 Sep 28;11(10):1932. doi: 10.3390/antiox11101932

Figure 2.

Figure 2

Effect of Dr-Nb(III) on the kinetics for peroxynitrite isomerization, at pH 7.0 and 22.0 °C. (A) Averaged time courses of the Dr-Nb(III)-catalyzed isomerization of peroxynitrite in the absence of CO2. The time course analysis according to Equation (1) allowed us to determine the following values of kobs: trace a, 7.3 × 10−1 s−1, R = 0.998; trace b, 1.8 s−1, R = 0.999. The Dr-Nb(III) concentration was: trace a, 1.0 × 10−5 M; trace b, 3.0 × 10−5 M. (B) Averaged time courses of the Dr-Nb(III)-catalyzed isomerization of peroxynitrite in the presence of CO2. The time course analysis according to Equation (1) allowed us to determine the following values of kobs: trace a, 1.5 × 101 s−1, R = 0.999; trace b, 1.7 × 101 s−1, R = 0.998. The Dr-Nb(III) concentration was: trace a, 1.0 × 10−5 M; trace b, 3.0 × 10−5 M. The CO2 concentration was 1.2 × 10−3 M. For clarity, trace b has been up-shifted of 0.3 units. (C) Dependence of kobs on the concentration of Dr-Nb(III) in the absence of CO2. Data were analyzed according to Equation (2) with kon = 4.7 × 104 M−1 s−1 and k0 = 3.1 × 10−1 s−1; R = 0.989, p = 0.0006. (D) Dependence of kobs on the concentration of Dr-Nb(III) in the presence of CO2. (E) Averaged time courses of peroxynitrite isomerization by apo-Dr-Nb in the absence of CO2. The time course analysis according to Equation (1) allowed us to determine the following values of kobs: trace a, 3.1 × 10−1 s−1; trace b, 2.7 × 10−1 s−1. The apo-Dr-Nb concentration was: trace a, 1.0 × 10−5 M; trace b, 3.0 × 10−5 M. For clarity, trace b has been up-shifted of 0.3 units. (F) Averaged time courses of peroxynitrite isomerization by apo-Dr-Nb in the presence of CO2. The time course analysis according to Equation (1) allowed us to determine the following values of kobs: trace a, 1.5 × 101 s−1; trace b, 1.6 × 101 s−1. The apo-Dr-Nb concentration was: trace a, 1.0 × 10−5 M; trace b, 3.0 × 10−5 M. For clarity, trace b has been up-shifted of 0.3 units. The CO2 concentration was 1.2 × 10−3 M. (G) Dependence of kobs on the concentration of apo-Dr-Nb in the absence of CO2. The symbol on the ordinate indicates the value of k0: 3.1 × 10−1 s−1. The average value of kobs obtained in the presence of apo-Dr-Nb is: 3.0 × 10−1 s−1. (H) Dependence of kobs on the concentration of apo-Dr-Nb in the presence of CO2. The symbol on the ordinate indicates the value of k0: 1.5 × 101 s−1. The average value of kobs obtained in the presence of apo-Dr-Nb and CO2 is: 1.5 × 101 s−1. In panels D, G, and H, the differences among the kobs values are not statistically significant. The peroxynitrite concentration was 2.0 × 10−4 M. The HCO3− concentration was 5.0 × 10−1 M. Where not shown, the standard deviation is smaller than the symbol.