19. Enzymes

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.

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b. Fresh pineapple is used in a marinade to tenderize tough meat. Why?

Why do enzymes function only under mild conditions?

Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of 7.7 to 8.0. How is the rate of a trypsin-catalyzed reaction affected by each of the following conditions?

a. changing the pH to 3.0

How would the following changes affect enzyme activity for an enzyme whose optimal conditions are normal body temperature and physiological pH?

a. raising the temperature from 37 °C to 60 °C

The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:

Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:

a. adding excess urea

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?

a. increasing the concentration of proteins

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?

c. running the reaction at 0 °C

Problems 10.94 and 10.95 both mention enzymes that hydrolyze peptide bonds. How do you account for the fact that pepsin has a high catalytic activity at pH 1.5 but chymotrypsin has very little activity at pH 1.5?

Meats spoil due to the action of enzymes that degrade the proteins. Fresh meats can be preserved for long periods of time by freezing them. Explain how freezing meats works to prevent spoilage.

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be given prior to consuming dairy products. (16.4, 16.5)

b. What might happen to the enzyme if the Lactaid were stored at 55 °C?