Figure 10.

Experiment-2 of the gastric acidic pH and pepsin (274 U/mL) effects (with describing model parameter estimates $\pm \mathrm{SE})$ on heat-treated GH5-tCel5A1 activity over a 5-h period after the gastric pH and pepsin buffer being mixed with the heat-treated crude GH5-tCel5A1 enzyme preparation for incubation at the resulting mixture pH = 3.5 and pepsin at 274 U/mL 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 GH5-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 and pepsin (274 U/mL) conditions established according to the exponential response model as: $\mathrm{Y}=73.926\left(\pm ,10.537\right){\mathrm{e}}^{(-\mathrm{x})}$, P < 0.0001 for the initial residual heat-treated tCel5A1 activity estimate; and P = 0.764 for the rate constant estimate; ${\mathrm{R}}^2=0.024$, n = 84; and alternatively, established according to the linear response model as $\mathrm{y}=73.947\left(\pm ,10.717\right)+1.100\left(\pm ,3.725\right)x$, P < 0.0001 for the intercept; and P = 0.769 for the slope, ${\mathrm{r}}^2=0.024$, 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 ± 21.379 at the 0-min exposure to the gastric pH-3.5 and pepsin-274 U/mL incubation) and incubation time under gastric pH 3.5 and pepsin (274 U/mL) conditions according to the exponential response model established as: $\mathrm{Y}=104.600\left(\pm ,14.337\right){\mathrm{e}}^{(-\mathrm{x})}$, P < 0.0001 for the initial residual heat treated GH5-tCel5A1 activity estimate; and P = 0.994 for the rate constant estimate, ${\mathrm{R}}^2=0.026$, n = 84; and according to the linear response model established as $\mathrm{y}=104.600\left(\pm ,14.343\right)+0.0391\left(\pm ,4.932\right)x$, P < 0.0001 for the intercept and P = 0.994 for the slope, ${\mathrm{r}}^2=0.026$, n = 84; (C) the Eadie-Hofstee linear plot between the heat-treated 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 $\mathrm{y}=38.483\left(\pm ,6.445\right)+1.053\left(\pm ,0.124\right)\mathrm{x}$, P < 0.0001 for all parameter estimates; ${\mathrm{r}}^2=0.524$, n = 72; and (D) the Eadie-Hofstee linear plot between the relative heat-treated GH5-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 ± 21.379) at the 0-min exposure to the gastric pH-3.5 and pepsin-274 U/mL incubation) and the v/t ratio established as $\mathrm{y}=51.280\left(\pm ,8.588\right)+1.053\left(\pm ,0.124\right)\mathrm{x}$, P < 0.0001 for all parameter estimates; ${\mathrm{r}}^2=0.524$, n = 72.