What is the reactant for each of the following enzymes?

a. galactase

What is the name of the class of enzymes that would catalyze each of the following reactions?

c. converting glucose (C₆H₁₂O₆) to fructose (C₆H₁₂O₆).

What is the name of the class of enzymes that would catalyze each of the following reactions?

a. addition of water to a double bond

What is the name of the class of enzymes that would catalyze each of the following reactions?

c. splitting peptide bonds in proteins

Match the terms (1) enzyme–substrate complex, (2) enzyme, and (3) substrate with each of the following:

b. the combination of an enzyme with the substrate

Match the terms (1) enzyme–substrate complex, (2) enzyme, and (3) substrate with each of the following:

a. has a tertiary structure that recognizes the substrate

Match the terms (1) active site, (2) lock-and-key model, and (3) induced-fit model with each of the following:

a. the portion of an enzyme where catalytic activity occurs

Write an equation that represents an enzyme-catalyzed reaction.

How is the active site different from the whole enzyme structure?

After the products have formed, what happens to the enzyme?

What are isoenzymes?

How is the LDH isoenzyme in the heart different from the LDH isoenzyme in the liver?

A patient arrives in an emergency department complaining of chest pains. What enzymes would you test for in the blood serum?

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

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?

b. running the reaction at 75 °C

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

a. changing the pH to 5.0

The following graph shows the activity versus pH curves for pepsin, sucrase, and trypsin. Estimate the optimum pH for each.

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Refer to the graph in problem 16.45 to determine if the reaction rate in each condition will be at the optimum rate or not.

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a. trypsin, pH 5.0

Indicate whether each of the following describes a competitive or a noncompetitive enzyme inhibitor:

a. The inhibitor has a structure similar to the substrate.

Indicate whether each of the following describes a competitive or a noncompetitive enzyme inhibitor:

d. The structure of the inhibitor is not similar to the substrate.

Oxaloacetate is an inhibitor of succinate dehydrogenase. 

a. Would you expect oxaloacetate to be a competitive or a noncompetitive inhibitor? Why?

Methanol and ethanol are oxidized by alcohol dehydrogenase. In methanol poisoning, ethanol is given intravenously to prevent the formation of formaldehyde that has toxic effects.

b. Would ethanol compete for the active site or bind to a different site?

In humans, the antibiotic amoxicillin (a type of penicillin) is used to treat certain bacterial infections.

a. Does the antibiotic inhibit enzymes in humans?

In humans, the antibiotic amoxicillin (a type of penicillin) is used to treat certain bacterial infections.

c. Is amoxicillin a reversible or irreversible inhibitor?

Ethylene glycol (HO—CH₂—CH₂—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.

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a. What class of enzyme catalyzes the reactions described?

Ethylene glycol (HO—CH₂—CH₂—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.

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b. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol. How might this help prevent toxic levels of oxalic acid in the body?

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)

a. What is the name of enzyme present in Lactaid, and what is the major class of this enzyme?

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?

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

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a. The directions for a gelatin (protein) dessert say not to add fresh pineapple. However, canned pineapple where pineapple is heated to high temperatures can be added. Why?

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?