Figure 7.

Experiment-2 of the gastric acidic pH effects (pH = 3.5) (with describing model parameter estimates $\pm \mathrm{SE})$ on the heat-treated GH5-tCel5A1 activity over a 5-h period after the gastric pH buffer being mixed with the heat-treated crude GH5-tCel5A1 enzyme preparation prior to further incubation for measuring cellulase activity with the carboxymethyl cellulose (CMC) substrate buffer in presence of dithiothreitol (DTT) (5 mM) and N₂ gas purging for 15 min at 37 °C. (A) Exponential plot of the inhibition kinetic relationship between the heat-treated tCel5A1 activity [v, mean $\pm \mathrm{SE},\mathrm{n}=12\mathrm{at}\mathrm{each}\mathrm{time}\mathrm{point},$ nmol/mg protein•min] and incubation time (t, h) under the gastric pH-3.5 conditions according to the exponential response model established as: $\mathrm{Y}=61.859\left(\pm ,8.079\right){\mathrm{e}}^{(-\mathrm{x})}$, P < 0.0001 for the initial residual heat-treated GH5-tCel5A1 activity estimate; and P = 0.103 for the rate constant estimate; ${\mathrm{R}}^2=0.059$, n = 84; and alternatively, according to the linear response model established as $\mathrm{y}=62.513\left(\pm ,7.345\right)-8.451\left(\pm ,4.358\right)\mathrm{x}$, P < 0.0001 for the intercept; and P = 0.056 for the slope, ${\mathrm{r}}^2=0.064$, n = 84; (B) Exponential plot of the inhibition kinetic relationship between the relative heat-treated GH5-tCel5A1 activity (v, mean $\pm \mathrm{SE},\mathrm{n}=12\mathrm{at}\mathrm{each}\mathrm{time}\mathrm{point},$ % of the control group measured at I_c of 100.000 ± 24.352) at 0-min exposure to the gastric pH 3.5 incubation) and incubation time (t, h) under gastric pH 3.5 conditions according to the exponential response model established as: $\mathrm{Y}=105.6\left(\pm ,13.791\right){\mathrm{e}}^{(-\mathrm{x})}$, P < 0.0001 for the initial residual heat-treated GH5-tCel5A1 activity estimate; and P = 0.103 for the rate constant estimate, ${\mathrm{R}}^2=0.059$, n = 84; and alternatively, according to the linear response model established as $\mathrm{y}=106.7\left(\pm ,12.537\right)-8.451\left(\pm ,4.358\right)\mathrm{x}$, P < 0.0001 for the intercept; and P = 0.056 for the slope, ${\mathrm{r}}^2=0.087$, n = 84; (C) the Eadie-Hofstee linear plot between the heat treated GH5-tCel5A1 enzyme activity [v, mean $\pm \mathrm{SE},\mathrm{n}=12\mathrm{at}\mathrm{each}\mathrm{data}\mathrm{point},$ nmol/mg protein•min] and the v/t ratio established as $\mathrm{y}=20.321\left(\pm ,3.744\right)+1.154\left(\pm ,0.105\right)\mathrm{x}$, P < 0.0001 for all the parameter estimates; ${\mathrm{r}}^2=0.649$, n = 72; and (D) the Eadie-Hofstee linear plot between the relative heat-treated tCel5A1 enzyme activity (v, mean $\pm \mathrm{SE},\mathrm{n}=12\mathrm{at}\mathrm{each}\mathrm{data}\mathrm{point},$ % of the control group measured at I_c of 100.000 ± 24.352 at 0-min exposure to the gastric pH 3.5 incubation) and the v/t ratio established as $\mathrm{y}=34.685\left(\pm ,6.391\right)+1.153\left(\pm ,0.105\right)\mathrm{x}$, P < 0.0001 for all parameter estimates; ${\mathrm{r}}^2=0.650$, n = 72.