Sigmaplot software version 12

Data are represented as mean ± standard error of the mean (SEM). Statistical analysis was performed by one-way analysis of variance followed by Tukey’s multiple comparison test. The analysis was performed using SigmaPlot software version 12.5 (San Jose, CA, USA). A P value < 0.05 was considered statistically significant.

All experiments were performed in triplicate and analyzed by ANOVA test and student t-test using the SigmaPlot software version 12.0 (CA, United States).

All treatments consisted of four experimental units in triplicate (n = 12). All data were verified for homoscedasticity and normality. The values for cell viability obtained from photoprotection and cytotoxicity bioassays were analyzed using one-way ANOVA followed by the Tukey–Kramer post-hoc test for multiple comparison. Sigma Plot software (version 12) was used for all statistical analyses. A p-value less than 0.05 was considered to indicate significant differences in all statistical analyses.

The comparison of a selenocysteine-dependent enzyme (TcTGR) with a Cys-dependent enzyme (EcTrxR), regarding its ability to catalyze the Trx-dependent reduction of H₂O₂, was evaluated by mixing 150 μM NADPH with either 60 μM TsTrx and 11.2 nM TcTGR or 6 μM EcTrx and 83 nM EcTrxR in TE buffer. The reaction was started by adding 1 mM H₂O₂, and the absorbance at 340 nm was measured. The final volume of the reaction mixture was 0.6 mL.
The kinetic constants K_m and k_cat of TsPrx1 and TsPrx3 for either H₂O₂, t-butyl hydroperoxide, or the cumene hydroperoxide substrates were determined by varying the concentration of the corresponding peroxide at a constant concentration of both NADPH (150 μM) and TsTrx (60 μM). To obtain the kinetic parameters for TsTrx, a constant concentration of 50 μM H₂O₂ was used at varying TsTrx concentrations. In all cases, fixed concentrations of TsPrxs (1.25 μM) and TcTGR (11.2 nM) were used (these last concentrations were previously determined to prevent them being limiting). The kinetic constants of TcTGR toward H₂O₂ was obtained by varying the concentration of the peroxide at a constant concentration of NADPH (150 μM) and TsTrx (60 μM). All initial velocity data were fitted to the Michaelis–Menten equation through non-linear regression analysis using Sigma-Plot Software version 12.