This set of Drug Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Drugs Biotransformation – Phase 2 Reactions”.
1. Which enzyme is important in the Phase II reactions?
Explanation: Phase II reactions involve the transfer of a suitable moiety such as glucuronic acid sulfate, glycine, etc. to the phase I reaction. This transfer is mediated by the presence of the enzyme Transferase.
2. The phase II reactions are detoxification pathways.
Explanation: In the phase, II reactions tissue reactive and carcinogenic metabolites are rendered harmless by conjugation with glutathione. The Phase II reactions terminate the pharmacologic activity of xenobiotics.
3. Which of the following is not a characteristic of the moieties that are transferred to the substrate in phase II reactions?
a) Simple endogenous molecules are transferred
b) Large molecular sized groups are attached
c) Strong polar groups are attached
d) Strong nonpolar groups are attached
Explanation: The moieties transferred to the substrates in a phase II reactions possess characteristics that are, simple endogenous molecules, large groups, and strong polar or ionic groups are attached to make the substrate water soluble.
4. Which of the following statement is false?
a) D-glucuronic acid is easily available
b) Several functional groups can be easily linked with the D-glucuronic acid
c) Conjugation with D-glucuronic acid occurs to a high degree
d) Whole animal kingdom have the common ability to produce D-glucuronic acid
Explanation: The statement d is false since all the mammals have the ability to produce glucuronides. D-glucuronic acid is readily available and can be easily conjugated with other functional groups.
5. Which coenzyme is synthesized in the 1st step of the formation of Glucuronide?
a) Uridine triphosphate
b) Uridine-5’-diphosphate-alpha-D-glucuronic acid
Explanation: Glucuronide formation takes place in 2 steps. The 1st step activated coenzyme uridine-5’-diphosphate-alpha-D-glucuronic acid is formed from UDP-glucose. The coenzyme acts as a donor of glucuronic acid.
6. Which enzyme is of the utmost importance for the 2nd step in the formation of Glucuronide?
d) UDP-glucuronyl transferase
Explanation: In the 2nd step of the formation of glucuronide, transfer of glucuronyl moiety from UDPGA to the substrate happens in the presence of enzyme UDP-glucuronyl transferase to form the conjugate.
7. Which one of the following is an example of Carboxyl compounds?
d) Salicylic acids
Explanation: These compounds form ester glucuronides. For example aryl acids, arylalkyl acids, salicylic acids, fenoprofen. Amides, Sulfonamides, Meprobamate, Sulfadimethoxine are amines or amides which form N-glucuronides.
8. In the sulfation process, what is the name of the coenzyme formed in the 1st step?
b) Adenosine triphosphate
d) Uridine-5’-diphosphate-alpha-D-glucuronic acid
Explanation: In the 1st step of sulphation, synthesis of an active coenzyme takes place. The coenzyme name is 3’-phosphoadenosine-5’-phosphosulfate. This coenzyme acts as a donor of sulfate to the substrate.
9. Which enzyme’s presence is of utmost importance for the 2nd step of sulphation?
d) UDP-glucuronyl transferase
Explanation: Sulfotransferase catalyses the transfer of sulphate group from 3’-phosphoadenosine-5’-phosphosulfate to the substrate. It also helps in the liberation of 3’-phosphoadenosine-5’-phosphate.
10. Which of the following is not an example of a drug undergoing acetylation reaction?
b) Salicylic acids
Explanation: Acetylation is an important metabolic pathway for drugs containing primary amino groups. Drugs which undergo acetylation reaction are histamine, sulphanilamide, and hydralazine. Acetylation may sometime lead to the production of toxic compounds.
Sanfoundry Global Education & Learning Series – Drug and Pharmaceutical Biotechnology.
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