Question

1)

In order to do an enzyme activity assay you must isolate your favorite enzyme from the cell. After isolating your enzyme you find that the active form of the enzyme is 6x the size that the primary structure would suggest. What is likely true about your enzyme?

a)It has denatured, but NOT aggregated

b) It has lost its original primary structure

c) It has quaternary structure

d) It has mostly beta-strand secondary structure

e) It has denatured and aggregated

You are studying enzyme “X” whose active site consists of 5 amino acids; 2 acidic amino acids and 3 amino acids with R-groups containing only non-polar covalent bonds. What chemical properties would you expect the substrate for enzyme “X” to have?

a) Hydrophobic and basic properties

b) No capacity to make hydrogen bonds, but able to make hydrophobic interactions

c) Hydrophobic and acidic properties

d) No capacity to make chemical interactions

e) Great capacity to form covalent bonds that would stabilize the substrate in the active site

Which of the following reactions could be coupled to ATP hydrolysis to make it energetically favorable or spontaneous? (“to” is equivalent to an arrow)

a) Creatine phosphate + H20 to creatine + Pi ΔG = -3.0

b) Glutamic acid + NH3 to glutamine ΔG=+3.

c) Glucose-1 phosphate + H2O to glucose + Pi ΔG= -5.0

d) Glucose + Pi to glucose-6 phosphate + H20 ΔG= +9.4

Answer 1

1)Answer c is correct (as the enzyme is 6x the size of primary structure so the enzyme has multiple subunits and has formed a hexamer so th only possible answer is ut has quaternary structure)

2) Answer c is correct ( as the active site has 2 acidic amino acids and 3 non polar amino acids which have hydrophobic residues on their R group. Hence in the active site these form hydrophobic interaction with acidic properties as 2 amino acids are acidic amino acids)

3) Answer is d ( because this reaction has high positive ∆G hence it needs coupling reaction i.e a exothermic reaction to make it favourable. So ATP hydrolysis is required in this reaction.)