Gateway Technical College BIO 806-177 Lecture 10 : Drug Design and Enzyme Regulation 1)Given the series of reactions: A  B  C  D  E with enzyme 1 catalyzing A ? B, enzyme 2 catalyzing B ? C, enzyme 3 catalyzing C ? D, and enzyme 4 catalyzing D ? E

1)Given the series of reactions: A  B  C  D  E with enzyme 1 catalyzing A ? B, enzyme 2 catalyzing B ? C, enzyme 3 catalyzing C ? D, and enzyme 4 catalyzing D ? E. Which of the following statements about feedback control in this series of reactions is CORRECT?

1. 1. If the product D inhibits enzyme 1, that is an example of product inhibition
   2. If the product B inhibits enzyme 4, that is an example of feedback inhibition
   3. If the product B inhibits enzyme 4, that is an example of product inhibiton
   4. If the product D inhibits enzyme 1, that is an example of feedback inhibition
2. Given the reaction network:

2. 1. Product F activates enzyme 2
   2. Product F inhibits enzyme 2
   3. Product D activates enzyme 1
   4. Product D inhibits enzyme 4
3. For a heteroallosteric inhibitor, what shape is the v vs. [S] curve under the effect of an activator? Under an inhibitor?
   1. Hyperbolic under an activator, sigmoidal under an inhibitor
   2. Sigmoidal under an activator, hyperbolic under an inhibitor
   3. Sigmoidal under an activator, sigmoidal under an inhibitor
   4. Hyperbolic under an activator, hyperbolic under an inhibitor
4. Which of the following statements about the enzyme aspartate carbamoyl transferase (ACTase) is correct?
   1. ACTase is solely controlled by the absolute levels of CTP in the cell
   2. The T ?? R transition is modulated by ATP vs. CTP binding away from the active site
   3. The conformational changes ACTase undergoes during the T ?? R transition do not involve changes to the quaternary structure
   4. The primary modulator of ACTase activity is the ratio of catalytic subunits to regulatory subunits in a complex
5. Which of the following statements about the quaternary structure aspartate carbamoyl transferase is CORRECT?
   1. It contains 6 subunits and is D3 symmetric
   2. It contains 12 subunits and is D3 symmetric
   3. It contains 24 subunits and is C3 symmetric
   4. It contains 6 subunits and is C3 symmetric
6. Proteases are first produced in an inactive “zymogen” and are only activated following cleavage by an activated protease. What biological reason for this is most CORRECT?
   1. Cleavage by an active protease in this way allows for a very rapid turning on and off protease activity in response to environmental stimuli
   2. It allows for their activation to only occur in a very specific tissues where protease activity is desired
   3. It is not possible for a single protein chain to confer protease activity, thus, the most efficient way for the cell to make proteases is to cleave a single chain into multiple chains
   4. Since peptide bond cleavage is energetically favorable, they can be used to deliver energy from one tissue type to another
7. Which of the following mechanism are NOT used to reversibly control enzyme activity?
   1. Substrate-level control through product inhibition
   2. Feedback control through heteroallosteric effectors
   3. Covalent modification by kinases/phosphates
   4. Protein backbone cleavage by proteases