This set of Protein Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Targets – Engineering Enzymes”.
1. Which of the following is an industrially important enzyme?
a) Arginase
b) Pyruvate carboxylase
c) Pyruvate kinase
d) Pectinases
View Answer
Explanation: Pectinases is an industrially important enzyme. Pectinase is a collective term that refers to a group of enzymes that degrade pectic substances in the cell wall of higher plants. Arginase, pyruvate carboxylase and pyruvate kinase are not industrially important enzymes.
2. Pectinase account for how much percent of global industrial enzymes produced?
a) 50 percent
b) 60 percent
c) 4 percent
d) 10 percent
View Answer
Explanation: Pectinase accounts for 10 percent of global industrial enzymes produced. Pectinases are a group of enzymes which cause degradation of pectin. Pectinases have wide applications in the fruit juice industry, wine industry, recycling of waste paper, textile industry, etc.
3. Which of the following is not true for enzymes?
a) Colloidal nature
b) High molecular weight
c) Susceptible to denaturation
d) Dialyzable
View Answer
Explanation: Enzymes are colloidal in nature, non-dialyzable, have high molecular weight, and are susceptible to denaturation. Hence, the statement that enzymes are dialyzable is not true. Biochemical reactions taking place within the living cells are catalyzed by enzymes.
4. The amount of enzyme is expressed in terms of its activity.
a) False
b) True
View Answer
Explanation: The above statement is true. The actual molar amount of enzyme cannot be determined and therefore it is unknown. Hence, the amount of enzyme is expressed in terms of its activity.
5. Which of the following is not a way to measure enzyme activity?
a) Katal
b) Turnover number
c) International unit
d) Unit of enzyme activity
View Answer
Explanation: The unit of enzyme activity is not a way to measure enzyme activity. Katal, specific activity, turnover number, and International unit are all ways of measuring enzyme activity. Specific activity (U/mg) is the number of units of enzyme activity per milligram of total protein present.
6. Which of the following property shows that enzymes are proteins?
a) Catalytic property
b) Structural property
c) Molecular weight
d) The proportion of C, H, N, and S
View Answer
Explanation: The proportion of C, H, N, and S in enzymes are similar to proteins. This property of the enzyme shows that enzymes are nothing but proteins. The catalytic property, structural property, and molecular weight do not show that enzymes are proteins.
7. Which of the following is not an industrially important enzyme?
a) Pectinase
b) Cellulase
c) Lysozyme
d) Arginase
View Answer
Explanation: Arginase is not an industrially important enzyme. It catalyzes the conversion of arginine to ornithine. Pectinase, cellulase, and lysozyme are industrially important enzymes. Cellulose catalyzes the decomposition of cellulose and some other related polysaccharides. Lysozyme cleaves the peptidoglycan component of bacterial cell walls, leading to cell death.
8. Enzymes are specific in nature.
a) False
b) True
View Answer
Explanation: The above statement is true. Enzymes are specific in nature. Specificity is the extra-ordinary ability of the enzymes to recognize a specific substrate and catalyze a specific reaction.
9. Which of the following is not a property of enzymes?
a) Catalytic power
b) Specificity
c) Acts as ampholytes
d) Irreversibility
View Answer
Explanation: Irreversibilityis not a property of enzymes. On the contrary, enzymes are reversible. Catalytic power, specificity, and acts as ampholytes are all properties of enzymes. Due to the catalytic power of enzymes, the cells can carry out reactions at low temperature, pressure, and in the dilute aqueous medium.
10. Seven Katal is equivalent to how many International units of enzymes?
a) 7 x 106 IU
b) 21 x 107 IU
c) 70 x 106 IU
d) 42 x 107 IU
View Answer
Explanation: Seven Katal is equivalent to 42 x 107 International units of enzymes.
Formula: 1 Katal=6 x 107 IU
Hence, 7 Katal=7 x 6 x 107 IU
7 Katal=42 x 107 IU.
11. Which of the following is not an application of pectinase?
a) Tea and coffee processing
b) Extraction of vegetable oil
c) Processing of animal feed
d) Recycling of plastics
View Answer
Explanation: Recycling of plastics is not an application of pectinase. The application of pectinases is tea and coffee processing, extraction of vegetable oil, processing of animal feed, etc. Although pectinase is used in the recycling of paper, it is not used in the recycling of plastics.
12. Which of the following is the way of expressing enzyme activity by measuring the amount of enzyme that catalyzes the formation of one micromole of product in one minute under optimal conditions of pH, temperature and ionic strength?
a) Specific activity
b) Katal
c) Turnover number
d) International unit
View Answer
Explanation: The International unit is the way of expressing enzyme activity by measuring the amount of enzyme that catalyzes the formation of one micromole of product in one minute under optimal conditions of pH, temperature, and ionic strength. One IU is the amount of enzyme that catalyzes the formation of one micromole of product in one minute under optimal conditions of pH, temperature, and ionic strength.
13. Which of the following is the number of units of enzyme activity per milligram of total protein present?
a) Katal
b) Turnover number
c) International unit
d) Specific activity
View Answer
Explanation: Specific activity (U/mg) is the number of units of enzyme activity per milligram of total protein present. Katal, specific activity, turnover number, and International unit are all ways of measuring enzyme activity.
14. Which of the following does not show that enzymes are proteins?
a) The proportion of C, H, N, and S
b) Susceptibility to denaturation
c) Enzymes act as ampholytes
d) High molecular weight
View Answer
Explanation: ‘High molecular weight’ property does not show that enzymes are proteins. The proportion of C, H, N, and S in enzymes are similar to proteins. Like proteins, enzymes act as ampholytes. They are susceptible to denaturation. These properties show that enzymes are proteins.
15. Which of the following is not a constituent enzyme of the pectinase group of enzymes?
a) Pectin methyl esterase
b) Pectin lyase
c) Polygalacturonase
d) Pectin ethyl esterase
View Answer
Explanation: Pectin ethyl esterase is not a constituent enzyme of the pectinase group of enzymes. Pectin methyl esterase, pectin lyase, and polygalacturonase are constituent enzymes of the pectinase group of enzymes.
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