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Questions and Answers
What is the primary role of acetyl CoA in the acetylation process?
What is the primary role of acetyl CoA in the acetylation process?
- To donate the acetyl group during conjugation (correct)
- To hydrolyze xenobiotics before metabolism
- To inhibit the action of acetyltransferases
- To remove hydroxyl groups from xenobiotics
Which of the following statements about methylation is accurate?
Which of the following statements about methylation is accurate?
- Most xenobiotics are primarily excreted as methylated conjugates.
- Methylation primarily involves the addition of hydroxyl groups.
- S-adenosylmethionine (SAM) is the active donor of methyl groups. (correct)
- Enzymes involved in methylation are called acetyltransferases.
What defines an individual as a 'slow' acetylator?
What defines an individual as a 'slow' acetylator?
- Having a high concentration of acetyltransferase enzymes
- Exhibiting enhanced metabolism of xenobiotics
- Metabolizing detoxifying agents faster than 'fast' acetylators
- Possessing polymorphic variants leading to reduced drug clearance (correct)
In the representation of the acetylation reaction, what do X and CoA represent?
In the representation of the acetylation reaction, what do X and CoA represent?
What is the result of glutathione conjugation in xenobiotic metabolism?
What is the result of glutathione conjugation in xenobiotic metabolism?
Flashcards
What is acetylation?
What is acetylation?
The process of attaching an acetyl group (CH3CO) to certain molecules, often drugs or toxins, to make them easier to eliminate from the body.
How does acetylation work?
How does acetylation work?
A molecule called Acetyl CoA acts as the supplier of the acetyl group. Enzymes called acetyltransferases help make the attachment happen.
What are 'fast' and 'slow' acetylators?
What are 'fast' and 'slow' acetylators?
Some people have enzymes that acetylate drugs faster than others. This affects how quickly a drug is broken down in the body.
What is S-adenosylmethionine (SAM)?
What is S-adenosylmethionine (SAM)?
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What's one way the body gets rid of chemicals?
What's one way the body gets rid of chemicals?
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Study Notes
Xenobiotic Metabolism: Glutathione Conjugation
- Xenobiotics (toxic compounds) react with glutathione (GSH) to form glutathione conjugates.
- The toxic compound (R) is converted to a non-toxic form (R-S-G).
- Glutathione conjugates are metabolised before excretion
- The glutamyl and glycinyl groups are removed from the glutathione molecule
- An acetyl group is added to the remaining cysteine amino acid
- The resulting compound (mercapturic acid) is then excreted in the urine
Acetylation
- Acetylation involves the conjugation of hydroxylated xenobiotics with an acetyl group.
- Acetyl CoA is the active donor of the acetyl group.
- The reaction is catalyzed by acetyl transferase enzymes in the liver and various other tissues.
- Individuals can be classified as slow or fast acetylators based on the variations in acetyltransferase enzymes.
- Variations in acetyltransferase enzymes can affect how quickly drugs are cleared from the blood (e.g., isoniazid for tuberculosis treatment).
Methylation
- Some xenobiotics are excreted as methylated conjugates.
- S-adenosylmethionine (SAM) is the active methyl donor.
- The reaction is catalyzed by methyl transferase enzymes.
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