Biochemistry of Bile FC Flashcards
Questions
Answers
What are the 4 components of bile? (From most to least)
Bile Acids
Phospholipids
Cholesterol
Bile Pigments
What is the enzyme for the rate limiting step in bile synthesis? What does it add? What 4 things does it require?
7alpha-hydroxylase
Add hydroxyl group to cholesterol
Requires NADPH, O2, Vitamin C, and Cytochrome P450
What enzyme is used in the second step of bile acid synthesis? What 3 things are required at this step? What two things are changed at this step?
12alpha-hydrozylase
NADPH, O2, and CoA
B-ring saturated and Propionyl-CoA obtained (where acid now is)
What two bile salts/acids are initially obtained before conjugation? Which one predominates in humans?
Cholic acid (predominates in humans, extra OH) Chenodeoxycholic acid
What two molecules are used to conjugate cholic/chenodeozycholic acid?
Taurine or glycine
What are the 4 primary bile salts?
Taurocholic acid
Glycocholic acid
Taurochenodeoxycholic acid
Clycochenodeoxycholic acid
What is the pH of bile?
Alkaline 7.6-8.4
How are secondary bile acids formed? What are the two major ones?
By intestinal bacteria
Deoxycholic acid and Lithocholic acid
Where are both primary and secondary acids reabsorbed? Which one can not be reabsorbed?
Ileum Lithocholic acid (cannot be reabsorbed due to limited solubility)
What does heme oxygenase do?
Converts heme to biliverdin
What does biliverdin reductase do?
Converts bilverdin to bilirubin
During what step of heme catabolism is carbon monoxide produced?
Heme oxygenase (heme to biliverdin)
What is readily reused after being oxidized at the heme oxygenase step?
Fe3+
How is bilirubin transported to the liver? Bound to what?
Blood
Bound to albumin