Q: Which of the following equations correctly represents the overall reaction catalyzed by enolase?

$$2\text{-PGA} \longrightarrow \text{PEP} + \text{H}_2\text{O}$$

Question 1

Which of the following best describes the primary antibacterial mechanism of lysozyme found in tears and egg whites?

Accepted Answer

It hydrolyzes the β(1→4) glycosidic bonds between N-acetylmuramic acid (Mur2Ac) and N-acetylglucosamine (GlcNAc) in bacterial cell walls.

Question 2

In the enolase-catalyzed reaction converting 2-phosphoglycerate (2-PGA) to phosphoenolpyruvate (PEP), what is the role of the two magnesium ions at the active site?

Accepted Answer

They stabilize the negative charges on the carboxylate and phosphate groups of 2-PGA during catalysis.

Question 3

Which amino acid residue in the enolase active site acts as a general acid to facilitate the elimination of the hydroxyl group during the conversion of 2-PGA to PEP?

Accepted Answer

Glu211

Question 4

A mutation in lysozyme that prevents it from binding to N-acetylmuramic acid (Mur2Ac) would most likely result in which of the following?

Accepted Answer

Loss of antibacterial activity due to inability to cleave bacterial cell wall polysaccharides.

Question 5

Which of the following best explains why lysozyme is effective against Gram-positive bacteria but less effective against Gram-negative bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane that protects the peptidoglycan layer from lysozyme.

Question 6

During the enolase-catalyzed reaction, which intermediate is formed before the elimination of water?

Accepted Answer

Enolate intermediate

Question 7

Which of the following equations correctly represents the overall reaction catalyzed by enolase?

Accepted Answer

$$2	ext{-PGA} \longrightarrow 	ext{PEP} + 	ext{H}_2	ext{O}$$

Question 8

Which structural feature of bacterial cell walls is specifically targeted by lysozyme?

Accepted Answer

The β(1→4) glycosidic bond between Mur2Ac and GlcNAc residues.

Question 9

A patient with a genetic deficiency in enolase would most likely exhibit which of the following symptoms?

Accepted Answer

Impaired glycolysis leading to decreased ATP production in muscle cells.

Question 10

Which of the following statements about the mechanism of lysozyme is correct?

Accepted Answer

Lysozyme uses general acid-base catalysis to cleave the glycosidic bond in peptidoglycan.

Question 11

In the enolase reaction, which amino acid residue is responsible for abstracting a proton from the substrate to form the enolate intermediate?

Accepted Answer

Lys345

Question 12

Which of the following best describes the role of water in the enolase-catalyzed reaction?

Accepted Answer

Water is eliminated from 2-PGA to form phosphoenolpyruvate.

Question 13

Which of the following is a direct consequence of lysozyme activity on bacterial cell walls?

Accepted Answer

Osmotic lysis of the bacterial cell due to weakened peptidoglycan.

Question 14

If a bacterial strain acquires a mutation that replaces the β(1→4) glycosidic bond with a β(1→3) bond in its cell wall, what is the most likely effect on lysozyme sensitivity?

Accepted Answer

The bacterium will become resistant to lysozyme.

Question 15

Which of the following best explains why magnesium ions are essential for enolase activity?

Accepted Answer

They stabilize the negative charges on the enolate intermediate, lowering the activation energy.

Question 16

A researcher is studying a new antibiotic that inhibits enolase. Which metabolic pathway would be directly affected in bacteria treated with this antibiotic?

Accepted Answer

Glycolysis

Question 17

Which of the following best describes the chemical change that occurs during the enolase-catalyzed reaction?

Accepted Answer

A dehydration reaction resulting in the formation of a double bond (enol) in PEP.

Question 18

Which of the following is the correct structure for the product of the enolase reaction?

Accepted Answer

$$	ext{CH}_2=	ext{C}(	ext{OPO}_3$$^{2-}$$)	ext{COO}^-$$

Question 19

Which of the following best explains the importance of lysozyme in human innate immunity?

Accepted Answer

It provides a first line of defense by degrading bacterial cell walls before pathogens can establish infection.

Lysozyme and Enolase: Mechanisms and Biological Roles

Guida di studio - Domande di pratica

Study guide - Flashcard