Amino Acids, Proteins, and Enzymes

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

a. Docs the antibiotic inhibit emzymes in humans?

b. Why does the antabiotic kill bacteria, but not humans?

c. Is anosicillin a reversible or irreversible inhabitor?

What is the chemical formula for hydroxyurea?

Fetal hemoglobin binds oxygen more tightly than does adult hemoglobin. Why do you think fetal hemoglobin functions differently than adult hemoglobin?

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.

a. Draw the condensed structural formulas for methanol and ethanol.

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

c. Would ethanol be a competitive or noncompetitive inhibitor of alcohol dehydrogenase?

What is the molar mass of hydroxyurea?

Ethylene glycol $\left(\mathrm{HO}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}\right)$ 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 added to a radiator to prevent freezing and boiling.

a. What class of enzyme catalyzes the reactions described?

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 added to milk and the milk then refrigerated for $24$ hours?

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

b. What might happen to the enzyme if the Lactaid were stored at ${55}^{\circ }C$ ?

What type of interaction would you expect between the following in a tertiary structure?

a. threonine and glutamine

b. valine and alanine

c. arginine and glutamate

What are some differences between each of the following pairs? 

a. a salt bridge and a disulfide bond

b. an $\alpha$ helix and collagen

c. $\alpha$ helix and $\beta$-pleated sheet

d. tertiary and quaternary structures of proteins

Aspartame, which is used in artificial sweeteners, contains the following dipeptide: 

a. What are the amino acids in aspartame?

b. How would you name the dipeptide in aspartame?

Seeds and vegetables are often deficient in one or more essential amino acids. Using the following table, state whether each combination provides all of the essential amino acids: 

a. rice and garbanzo beans.

b. lima beans and cornmeal.

c. garbanzo beans and lima beans.

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

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?

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

c.  What structural level of a protein does the bromelain enzyme destroy?

Seeds and vegetables are often deficient in one or more essential amino acids. Using the table in problem, state whether each combination provides all of the essential amino acids. 

a. rice and lima beans.

b. rice and oatmeal.

c. oatmeal and lima beans.

Identify the amino acids and type of interaction that occurs between the following  R groups in tertiary protein structures:

a)

b)

c)

d)

a. Draw the condensed structural formula for Ser-Lys-Asp. 

b. Would you expect to find this segment at the center or at the surface of a protein? Why?

a. Draw the condensed structural formula for Val-Ala-Leu. 

b. Would you expect to find this segment at the center or at the surface of a protein? Why?

What are sonse differences between each of the following pairs? (16.1, 16.2. 16.3)

a. secondary and tertiary protein structures

b. exsential and nonessential amino acids

c. polar and nonpolar amino acids

d. dipeptides and tripeptides

Indicate whether ench of the following would be a substrate $\left(S\right)$ or an enzyme $\left(E\right):$ $(16.4)$

$a.$ lactose

$b.$ lipase

$c.$ amylase

$d.$ trypsin

$e.$ pyruvate

$f.$ transaminase

Indicate whether each of the following would be a substrate$\left(S\right)$or an enzyme $\left(E\right):$ $(16.4)$

$a.$ lactose

$b.$ lipase

$c.$ amylase

$d.$ trypsin

$e.$pyruvate

$f.$ transaminase

 Indicate whether eachof the following would be a substrate $\left(S\right)$or an enzyme $\left(E\right):$ $(16.4)$

$a.$ lactose

$b.$ lipase

$c.$ amylase

$d.$ trypsin

$e.$ pyruvate

$f.$ transaminase

If glutamate were replaced by proline in a protein, how might the tertiary structure be affected? $(16.1, 16.3)$

If glycine were replaced by alanine in a protein, how might the tertiary structure be affected? $(16.1,16.3)$

How do enzymes differ from catalysts used in chemical laboratories? $(16.4)$

Why do enzymes function only under mild conditions? $(16.4,16.5)$

If a blood test indicates a high level of $\mathrm{LDH}$ and $CK,$what could be the cause?

If a blood test indicates a high level of $ALT,$ what could be the cause? 

Consider the amino acids lysine, valine, and aspartate in an enzyme. State which of these amino acids have $R$ groups that would:

a. be found in hydrophobic regions.

b. be found in hydrophilic regions.

c. form hydrogen bonds.

d. form salt bridges.

How would the lock-and-key model explain that sucrase hydrolyzes sucrose, but not lactose? 

16.78 How does the induced-fit model of enzyme action allow an enzyme to catalyze a reaction of a group of substrates? 

Consider the amino acids histidine, phenylalanine, and serine in an enzyme. State which of these amino acids have $\mathrm{R}$ groups that would:

a. be found in hydrophobic regions

b. be found in hydrophilic regions

c. form hydrogen bonds

d. form salt bridges

$16.72$Maltase is an enzyme that hydrolyzes maltose to two glucose molecules. $(16.4)$

$a.$ What are the reactants and products of the reaction?

$b.$Draw an energy diagram for the reaction with and without maltase.

$c.$ How does maltase make the reaction go faster?

Indicate whether each of the following would be a substrate (S) or an enzyme (E): (16.4)

a. glucose

b. hydrolase

c. maleate isomerase

d. alanine

e. amylose

f. lactase

Lactase is an enzyme that hydrolyzes lactose to glucose and galactose.

a. What are the reactants and products of the reaction?

b. Draw an energy diagram for the reaction with and without lactase.

c. How does lactase make the reaction go faster?

Give the substrate of each of the following enzymes: (16.4)

a. urease

b. succinate dehydrogenase

c. aspartate transaminase

d. tyrosinase

Give the substrate of each of the following enzymes: $(16.4)$

a. maltase

b. fructose oxidase

c. phenolase

d. sucrase$(16.4)$