Porcine Pancreatic Alpha-Amylase
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Affect of pH on Porcine Pancreatic Alpha-Amylase Activity
Introduction
Proteins function in a variety of different ways, and one of their fundamental tasks is to act as enzymes. Enzymes are extremely important in controlling reaction speed (by initiating and regulating biological activity), cell communication, and growth. One particularly significant enzyme is amylase, which catalyzes the hydrolysis of alpha glycosidic linkages of amylose, starch components, and other oligosaccharides (Qian, et al., 1994).
Porcine pancreatic alpha-amylase can be found in pancreatic secretions, and works most efficiently at pH 6.9 for the majority of substrates. This ideal pH, however, has shown to shift to as low as 5.2 for the hydrolysis of some …show more content…
1994). Analysis shows the shift of the ideal pH down to 5.2 occurs only when the fifth sub-site is being occupied by the glucosyl residue of the specific substrate (Sivaramakrishnan, et al., 2006).
This indicates the way a substrate binds to the enzyme, directly affects its catalytic power as well as pH.
In this experiment, the six tubes which contained the same amount of enzyme to substrate were tested for reaction rate with pHs ranging from 4 to 9 as the only difference, in order to determine what the optimum pH was. According to previous experiments, protenation of the nucleophile limits catalysis at low pH, and deprotenation of the hydrogen donor limits it at high pH (Nielsen, Vriend & Borchert, 2001). In addition, a review paper states alpha-amylase …show more content…
One could argue the standard deviation is too large for the pH 6 to have a credible mean. This could be due to error in terms of how time was taken, also in when it was decided the solution no longer had starch. In terms of time, some groups may not have started the time as soon as the enzyme and substrate were together, while others may have not taken consistent ten-second intervals. As for the iodine test
3
for starch, knowing when the starch is gone is relative to the person conducting the experiment.
The initial color change is subjective, because there could still be starch in a solution if the iodine is an amber color but has specks of dark blue in the well which could cause some to state the reaction time as earlier than it actually is. There are several other human errors that could have resulted in a lower optimal pH, one of the biggest being contamination. If one did not use a different pipette, solutions will become contaminated with other pH levels.
A great majority of journals have experimentally found the optimal pH for pancreatic alpha-amylase to be between 6.7 and 6.9 (Nielsen, et al., 2001). While the ideal pH has
Affect of pH on Porcine Pancreatic Alpha-Amylase Activity
Introduction
Proteins function in a variety of different ways, and one of their fundamental tasks is to act as enzymes. Enzymes are extremely important in controlling reaction speed (by initiating and regulating biological activity), cell communication, and growth. One particularly significant enzyme is amylase, which catalyzes the hydrolysis of alpha glycosidic linkages of amylose, starch components, and other oligosaccharides (Qian, et al., 1994).
Porcine pancreatic alpha-amylase can be found in pancreatic secretions, and works most efficiently at pH 6.9 for the majority of substrates. This ideal pH, however, has shown to shift to as low as 5.2 for the hydrolysis of some …show more content…
1994). Analysis shows the shift of the ideal pH down to 5.2 occurs only when the fifth sub-site is being occupied by the glucosyl residue of the specific substrate (Sivaramakrishnan, et al., 2006).
This indicates the way a substrate binds to the enzyme, directly affects its catalytic power as well as pH.
In this experiment, the six tubes which contained the same amount of enzyme to substrate were tested for reaction rate with pHs ranging from 4 to 9 as the only difference, in order to determine what the optimum pH was. According to previous experiments, protenation of the nucleophile limits catalysis at low pH, and deprotenation of the hydrogen donor limits it at high pH (Nielsen, Vriend & Borchert, 2001). In addition, a review paper states alpha-amylase …show more content…
One could argue the standard deviation is too large for the pH 6 to have a credible mean. This could be due to error in terms of how time was taken, also in when it was decided the solution no longer had starch. In terms of time, some groups may not have started the time as soon as the enzyme and substrate were together, while others may have not taken consistent ten-second intervals. As for the iodine test
3
for starch, knowing when the starch is gone is relative to the person conducting the experiment.
The initial color change is subjective, because there could still be starch in a solution if the iodine is an amber color but has specks of dark blue in the well which could cause some to state the reaction time as earlier than it actually is. There are several other human errors that could have resulted in a lower optimal pH, one of the biggest being contamination. If one did not use a different pipette, solutions will become contaminated with other pH levels.
A great majority of journals have experimentally found the optimal pH for pancreatic alpha-amylase to be between 6.7 and 6.9 (Nielsen, et al., 2001). While the ideal pH has