Biotechnology 2nd Edition By David P. Clark – Test Bank

Chapter 11: Protein Engineering

1. Which of the following enzymes are used by industry and are potential targets for protein engineering:
a. Invertase
b. Rennet
c. Catalase
d. Amylase
e. Glucose isomerase
*f. All of the above
g. Some of the above

2. Disulfide bonds are involved in which of the following properties of proteins
a. Maintaining the 3D structure.
b. Minimizing oxidative damage.
c. Increasing the melting temperature of the protein
*d. All of the above.
e. None of the above.

3. In addition to disulfide bonds, other ways to increase the stability of a protein include:
a. Replacing flexible amino acids like glycine with more rigid amino acids like proline
b. Filling small cavities in the protein surface by replacing small hydrophobic amino acids with larger hydrophobic amino acids.
c. Replacing asparagine or glutamine with aspartic acid or glutamic acid, respectively.
*d. All of the above.
e. None of the above.

4. With respect to the binding sites of lactate dehydrogenase, which of the following statement is true:
a. The overall enzymatic activity is destroyed when any amino acid is changed.
b. The binding of substrates can be changed but the binding of cofactors cannot be changed.
c. The active site can be made larger and more hydrophobic but still only lactic acid can be the substrate.
*d. Changing a hydrophobic amino acid in the cofactor pocket to a positively charged amino acid will allow this enzyme to now prefer NADP rather than NAD.

5. With respect to beta-galactosidase activity, which of the following statements is true:
a. Beta-galactosidase is much smaller than most other hydrolytic enzymes.
*b. It may be possible to engineer a smaller version of beta-galactosidase that still functions.
c. From an industrial viewpoint, it would be far better to manufacture a larger version of beta-galactosidase.
d. All of these statements are true.

6. Directed evolution is a technique used to later the function of enzymes without needing structural data. Which of the following approaches are used in directed evolution.
a. Different domains of various proteins can be recombined together to create new enzymes.
b. Target mutagenesis of the putative active site can be carried out to alter enzyme function.
c. A cloned gene can be mutated using error-prone PCR and then new enzymes functions selected.
*d. All of the above are appropriate approaches.
e. Some of the above are appropriate approaches.

7. The steps involved in engineering new proteins that contain non-natural amino acids include
a. Cloning and directed evolution of a gene for tRNA synthetase to create the new tRNA charged with the non-natural amino acid.
b. Engineering genes for the new tRNA so it will bind to the amber codon.
c. Cloning all of these evolved genes into Methanococcus jannaschii.
d. All of the above.
*e. Some of the above.

8. Which of the following alterations has been used to expand the genetic code?
a. tRNAs have been developed that recognize four nucleotides rather than three
b. tRNAs synthetases have been engineered to add non-natural amino acids to amber tRNAs
c. “Photo-caged” amino acids replace natural amino acids during protein synthesis
d. Non-natural amino acids are used to cross-link the engineered proteins
*e. All of the above have been used
f. Some of the above have been used

9. Which of the following is not a role for non-natural amino acids in engineered proteins?
a. Provide reactive chemical groups
b. Provide reactive groups that are activated by UV light
c. Provide a fluorescent group for visualizing the protein
d. Provide a label for NMR spectroscopy
*e. Provide a new site for FokI endonuclease

10. When the DNA binding domain of FokI is combined with the recognition domain of the Gal4 activator, the result is
a. A recombinant protein with Zinc finger binding.
b. A restriction enzyme that cuts right in the middle of the Gal4 DNA recognition sequence.
*c. A nuclease that recognizes the GAL4 DNA recognition sequence and cuts next to it.
d. An endonuclease that cuts nonspecifically.