Figure 11.

Experiment-2 of the gastric acidic pH and pepsin (274 U/mL) effects (with describing model parameter estimates $\pm \mathrm{SE})$ on GH5-p4818Cel5_2A activity over a 5-h period after the gastric pH and pepsin buffer being mixed with the GH5-p4818Cel5_2A 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) Linear plot of the inhibition kinetic relationship between the GH5-p4818Cel5_2A 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 linear response model as: $\mathrm{y}=85.348\left(\pm ,3.415\right)-12.702\left(\pm ,1.187\right)\mathrm{x}$, P < 0.0001 for all parameter estimates; ${\mathrm{r}}^2=0.606$, n = 84; and alternatively, according to the exponential response model established as $\mathrm{Y}=89.186\left(\pm ,4.359\right){\mathrm{e}}^{[-0.227(\pm 0.026)\mathrm{x}]}$, P < 0.0001 all parameter estimates; ${\mathrm{R}}^2=0.581$, n = 84; (B) Linear plot of the inhibition kinetic relationship between the relationship of relative GH5-p4818Cel5_2A 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 ± 4.416) 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 linear response model established as: $\mathrm{y}=102.1\left(\pm ,4.088\right)-15.202\left(\pm ,1.421\right)\mathrm{x}$, P < 0.0001 for all parameter estimates, ${\mathrm{r}}^2=0.606$, n = 84; and established according to the exponential response model as $\mathrm{Y}=106.7\left(\pm ,5.218\right){\mathrm{e}}^{[-0.227(\pm 0.026)\mathrm{x}]}$, P < 0.0001 all parameter estimates, ${\mathrm{R}}^2=0.581$, n = 84; (C) the Eadie-Hofstee linear plot between the GH5-p4818Cel5_2A 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 $\mathrm{y}=26.418\left(\pm ,2.663\right)+0.829\left(\pm ,0.069\right)\mathrm{x}$, P < 0.0001 for all parameter estimates, ${\mathrm{r}}^2=0.677$, n = 72; and (D) the Eadie-Hofstee linear plot between the relative GH5-p4818Cel5_2A 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 ± 4.416) at the 0-min exposure to the gastric pH-3.5 and pepsin-274 U/mL incubation) and the v/t ratio established as $\mathrm{y}=31.618\left(\pm ,3.187\right)+0.829\left(\pm ,0.070\right)\mathrm{x}$, P < 0.0001 for all parameter estimates, ${\mathrm{r}}^2=0.677$, n = 72.