19. Enzymes

Name an enzyme that acts on each molecule.

c. RNA

What classes of enzymes would you expect to catalyze the following reactions?

c.

What kind of reaction does each of these enzymes catalyze?

b. A transmethylase

What kind of reaction does each of these enzymes catalyze?

c. A reductase

Alcohol dehydrogenase (ADH) catalyzes the following reaction. To what class of enzymes does ADH belong?

Which of the following reactions can be catalyzed by a decarboxylase?

a.

b.

Identify and describe the chemical change in the lyase-catalyzed reaction in Table 19.4 that involves fumarate and malate. Identify the substrate(s) and product(s).

Answer questions (a)–(e) concerning the following reaction:

a. The enzyme involved in this reaction belongs to what class of enzymes?

The meat tenderizer used in cooking is primarily papain, a protease enzyme isolated from the fruit of the papaya tree. Why do you suppose papain is so effective at tenderizing meat?

The reaction that follows is catalyzed by isocitrate dehydrogenase and occurs in two steps, the first of which (step A) is formation of an unstable intermediates (shown in brackets).

d. To what class of enzymes does isocitrate dehydrogenase, the enzyme that catalyzes this reaction, belong?

Serotonin is a monoamine neurotransmitter. It is formed in the body from the amino acid tryptophan. What class of enzyme catalyzes each of the two steps that convert tryptophan to serotonin?

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

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?