This set of Protein Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Targets – Engineering Stability”
1. Which of the following is the recognition sequence of Hind III restriction enzyme?
a) GCAACC
b) CCGCGG
c) TTGCAA
d) AAGCTT
View Answer
Explanation: The Hind III is a restriction endonuclease enzyme. It cleaves the DNA molecule at specific locations within the DNA molecule to produce staggered ends (or sticky ends). AAGCTT is the recognition sequence of Hind III restriction enzyme.
2. The amount of enzyme produced by a micro-organism is not increased by increasing the number of gene copies that code for it.
a) True
b) False
View Answer
Explanation: The above statement is false. The amount of enzyme produced by a micro-organism may be increased by increasing the number of gene copies that code for it. This principle has been used to increase the activity of penicillin-G-amidase in Escherichia coli.
3. Which of the following is a feature of critical importance in biotechnology?
a) Viscosity
b) Fluidity
c) pH
d) Stability
View Answer
Explanation: Stability is a feature of critical importance in biotechnology. Therefore, it is pursued with intense efforts. Viscosity, fluidity, and pH are not features of critical importance in biotechnology. Stability of various biological products is of immense importance.
4. Which of the following is concerned with stability to temperature?
a) Detergent processing
b) Beer processing
c) Leather processing
d) Food processing
View Answer
Explanation: The food and chemical processing is concerned with stability to temperature. They easily get deteriorated above a threshold temperature. Detergent processing, beer processing, and leather processing are not concerned with stability to temperature.
5. Several thermophilic proteins have additional ion pairs as compared to their mesophilic homologous.
a) False
b) True
View Answer
Explanation: The above statement is true. Ionic interactions or salt bridges stabilize the protein structure at elevated temperature. Hence, several thermophilic proteins have additional ion pairs as compared to their mesophilic homologous.
6. Substitutions of large hydrophobic residues in the protein cores with smaller amino acids have which of the following effect on the whole protein?
a) No effect on stability
b) Both stabilizing and destabilizing effect
c) Stabilizing effect
d) Destabilizing effect
View Answer
Explanation: Substitutions of large hydrophobic residues in the protein cores with smaller amino acids have destabilizing effect on the whole protein. This happens probably because cavities are created within the protein structure.
7. Binding of metal ions or cofactors can increase structural stability when they bind with higher affinity to the folded than to the unfolded state.
a) False
b) True
View Answer
Explanation: The above statement is true. Binding of metal ions or cofactors can increase structural stability when they bind with higher affinity to the folded than to the unfolded state. Binding sites for metal ions, frequently Ca+2, Zn+2, Cu+2 aims to enhance protein stability.
8. Which of the following is concerned with stability to pH?
a) Leather
b) Beer
c) Food
d) Detergents
View Answer
Explanation: Detergents are surfactants or mixture of surfactants that has cleaning properties due to its ability to greatly reduce the surface tension of water when used in very low concentrations. Leather, beer, and food are not concerned with stability to pH.
9. Only stability to temperature is important in industrial processes.
a) True
b) False
View Answer
Explanation: The above statement is false. Stability to temperature is not the only parameter that is important in industrial processes. Increase in oxidation stability, stability to alkali, and to proteases are also important.
10. Which of the following is not a method to stabilize a protein?
a) Immobilization techniques
b) Chemical modifications
c) Addition of stabilizing compounds
d) Reducing hydrophobic residues
View Answer
Explanation: Reducing hydrophobic residues is not a method to stabilize a protein. Hydrophobic residues are usually present on the surface of a globular protein, whereas hydrophilic residues are present in the core of the protein. Immobilization techniques, chemical modifications, and addition of stabilizing compounds are methods to stabilize a protein molecule.
11. Which of the following is the most prominent example of substance that is concerned with stability to proteolytic cleavage?
a) Foods
b) Beer
c) Detergent
d) Drugs
View Answer
Explanation: Drugs are the most prominent example of substance that is concerned with stability to proteolytic cleavage. Many drugs are sensitive to proteolytic cleavage in the body, thus rendering them ineffective. Foods, beers, and detergents are not prominent examples of substances that are concerned with stability to proteolytic cleavage.
12. Which of the following is not a method of immobilization?
a) Entrapment into gels
b) Encapsulation
c) Adsorptive interaction
d) Engulfment
View Answer
Explanation: Engulfment is not a method of immobilization. Entrapment into gels, Encapsulation, and Adsorptive interaction are various methods of immobilization. Immobilization techniques are the methods to stabilize proteins.
13. Unfavorable pH of the medium can often result in the inactivation of the involved enzymes.
a) False
b) True
View Answer
Explanation: The above statement is true. Unfavorable pH of the medium can often result in the inactivation of the involved enzymes. The change in the ionization of active /inactive site amino acid residues can produce a catalytically inactive unchanged protein molecule.
14. Which of the following interactions stabilize proteins by restricting the possible conformation of the unfolded proteins?
a) Non-covalent interactions
b) Vander Waals interactions
c) Hydrophobic interactions
d) Di-sulfide interactions
View Answer
Explanation: Di-sulfide interactions stabilize proteins by restricting the possible conformation of the unfolded proteins. Di-sulfide interactions are covalent bonds in nature and are therefore strong interactions. Non-covalent interactions, Vander Waals interactions, and hydrophobic interactions do not stabilize proteins by restricting the possible conformation of the unfolded proteins.
15. Which of the following cannot be used as an additive for stabilization of enzymes?
a) Sugars
b) Polyhydric alcohols
c) Some organic solvents
d) Urea
View Answer
Explanation: Urea cannot be used as an additive for stabilization of enzymes. It is a denaturating agent. Sugars, polyhydric alcohols, and some organic solvents are some of the additives that can be used for the stabilization of enzymes.
Sanfoundry Global Education & Learning Series – Protein Engineering.
To practice all areas of Protein Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.
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