Enzymes and Energy
In general, enzymes are protein molecules which must be folded in a specific three-dimensional shape in order to function properly. Certain environmental parameters can affect enzyme activity, including pH and temperature. If an enzyme’s shape changes significantly and it can no longer function, the enzyme is said to have become denatured.
The enzyme pancreatic amylase is manufactured and secreted by the pancreas into the duodenum (the large, beginning portion of the small intestine). Pancreatic amylase breaks down starch into maltose, a disaccharide. Pepsin is an enzyme that is released by the epithelium of the stomach, and functions in the stomach to break down proteins into smaller polypeptide units.
The following graphs show the activities of various enzymes under various environmental conditions.
Trypsin is a protein digesting enzyme that functions in the small intestine. Which of the following statements should be true about trypsin?
|A||The optimum pH for the functioning of trypsin is approximately 2.|
|B||Both trypsin and pepsin would be expected to be found working together in the same part of the body.|
|C||The optimum pH for the functioning of trypsin is approximately 8.5.|
|D||Trypsin could function well in a solution containing 1 molar hydrochloric acid.|
The key here is to understand that trypsin, like pancreatic amylase, functions in the small intestine, and therefore must have a similar optimal pH as does pancreatic amylase. The graph shows that optimum as 8.5. For the same reasons stated above for pepsin and pancreatic amylase, pepsin and trypsin could never work under similar conditions (choice B). Additionally, both choices A and D must be incorrect because they demand that trypsin could function at pH 2 and 0 (the pH of 1M HCl, which you should at least know is acidic).