This set of Enzyme Technology Multiple Choice Questions & Answers (MCQs) focuses on “Future Prospects – Unnatural Substrates”.
1. The development of genetically improved enzymes and of novel enzyme-like catalysts is undertaken by molecular biologists and organic chemists respectively.
a) True
b) False
View Answer
Explanation: The development of genetically improved enzymes and of novel enzyme-like catalysts is undertaken by molecular biologists and organic chemists respectively due to the following reasons:
• New enzymes are either sorted in the natural environment or by strain selection.
• Established industrial enzymes are being used in as wide a variety of ways as can be conceived.
• With the help of genetic engineering, novel enzymes are being designed.
• Also with the knowledge of enzymology, new organic catalysts are being designed and synthesized.
• More complex enzyme systems are being utilized.
Each of these areas has an extensive and rapidly expanding literature. Some advances possibly belong more properly to other areas of science. Thus, the above statement is true.
2. Many enzymes are not totally specific for their natural substrates.
a) True
b) False
View Answer
Explanation: Certain enzymes catalyze reaction very differently from those which it normally does and as reflected in their name and EC number. When these enzymes are placed in a not so usual environment, they display new activities. For example, lipases act as transesterases in non-aqueous environment. But for certain enzymes, the change in the physical environment is not necessary. Hence the above statement is true.
3. Lipases act as ____________ in primarily non-aqueous environments.
a) oxidoreductases
b) isomerases
c) transesterases
d) lyases
View Answer
Explanation: Lipases act as transesterases in primarily non-aqueous environments. Oxidoreductases which involve redox reactions in which hydrogen or oxygen atoms or electrons are transferred between molecules. Isomerases that catalyze molecular isomerization’s. Lyases which involve elimination reactions in which a group of atoms is removed from the substrate.
4. Other than oxygen, which of the following is an oxidant for glucose oxidase?
a) Benzoquinone
b) D-glucono-1,5-lactone
c) D-Carnitine
d) Hydroquinone
View Answer
Explanation: Glucose oxidase is specific for its D-glucose, but fairly non-specific in its choice of oxidant, normally molecular oxygen. It has been found that benzoquinone acts as an oxidant, which acts on glucose forming D-glucono-1,5-lactone and hydroquinone. The acetylcholinesterase has been found to catalyze the stereospecific hydrolysis of acetyl -D-carnitine but not acetyl-L-carnitine producing D-Carnitine.
5. What does X represent in the following reaction?
Β-D-Glucose + benzoquinone \(\underset{X}{\rightarrow}\) D-glucono-1,5-lactone + Hydroquinone
a) Acetylcholine esterase
b) Glucose oxidase
c) Lipase
d) Papain
View Answer
Explanation: In the above reaction, ‘X’ represents glucose oxidase enzyme which acts on glucose specifically, but the oxidant is different producing D-glucono-1, 5-lactone and hydroquinone. Acetylcholinesterase catalyzes the hydrolysis of acetylcholine. Lipases act as transesterases in primarily non-aqueous environments. Papain is a protease that is used for meat tenderization.
6. What does ‘Y’ represent in the following reaction?
Acetylcholine + water \(\underset{Y}{\rightarrow}\) Choline + acetic acid
a) Acetylcholine esterase
b) Glucose oxidase
c) Rennet
d) Papain
View Answer
Explanation: In the above reaction, ‘Y’ represents acetylcholine esterase which catalyzes the hydrolysis of acetylcholine releasing choline and acetic acid as products. Acetylcholine is the excitatory neurotransmitter in the synaptic junctions of vertebrates. Glucose oxidase is specific for D-glucose but fairly non-specific in its choice of oxidant, normally molecular oxygen. Rennet is used in cheese making. Papain is used in meat tenderization.
7. What does ‘Z’ represent in the reaction?
Acetyl – D – carnitine + water \(_{\overrightarrow{Acetylcholine \,esterase}}\) Z + acetic acid
a) D – carnitine
b) Choline
c) Hydroquinone
d) L -carnitine
View Answer
Explanation: In the above reaction, ‘Z’ represents D – carnitine which is produced by the action of acetylcholine esterase on acetyl – D – carnitine. L – carnitine cannot be produced as acetylcholine esterase is specific in action on acetyl – D – carnitine, rather than acetyl – L – carnitine. Choline is produced by the action of acetylcholine esterase on acetylcholine. Hydroquinone is produced when glucose oxidase acts on glucose and benzoquinone, rather than oxygen as the oxidant.
Sanfoundry Global Education & Learning Series – Enzyme Technology.
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