9 Questions
What is the main function of Cytochrome P450 in Phase I reactions?
Mono-oxygenation of xenobiotics
Which enzyme is responsible for glucuronidation in Phase II reactions?
UDP-glucuronosyltransferase
What happens to the activity of the original xenobiotic after Phase II reactions?
It decreases
Which phase leads to a greater increase in water-solubility of xenobiotics?
Phase II
Which chemical group is NOT utilized in Phase II reactions?
Nitrate
What role does NADPH2 play in Phase I reactions?
Reduction of one oxygen atom into substrate
Which tissue has the highest concentration of the enzyme catalyzing reactions with xenobiotics?
Liver
'Glycine conjugate' is formed during which type of conjugation in Phase II reactions?
'Amino acid conjugation'
'Glucuronic acid conjugate' increases the water-solubility of xenobiotics, leading to their excretion via which route?
'Feces'
Study Notes
- Biotransformation involves the chemical transformation of endogenous and exogenous substances in the body, including xenobiotics like pesticides, medicine, and food additives.
- The liver plays a crucial role in biotransformation, with enzymes mediating the process and altering the biological activity of metabolites.
- Biotransformation occurs in two phases: Phase I involves adding functional groups like -OH or -COOH to increase water-solubility, while Phase II adds larger chemical groups like glucuronide or sulfate for further water-solubility.
- Phase I reactions include oxidation, reduction, and hydrolysis, with enzymes like alcohol dehydrogenase and cytochrome P450 playing important roles.
- Phase II reactions involve conjugating larger, hydrophilic chemical groups to xenobiotics to enhance water-solubility, leading to the loss of the original xenobiotic activity.
Test your knowledge on biotransformation and detoxification processes involving endogenous chemical species and xenobiotics. Explore the metabolism of biologically active chemicals of external origin and toxic metabolites, such as pesticides, medicines, and food additives.
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