Flashcards in Ketone Bodies Deck (17)
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1
Where are ketone bodies produced?
mitochondrial matrix of Liver cells( only when acetyl-CoA levels are higher than CTC capacity)
- allow for energy of peripheral tissues
2
Ketoacidosis
High concentration of ketone bodies in the blood stream
subsections are
- high in blood (ketonemia)
- high in urine (ketonuria)
3
3-KA-CoA thiolase
Enzyme that catalyzes the 1st step of ketogenesis
Takes 2 acetyl CoA and forms Acetoacetyl-CoA
4
HMG-CoA synthase
Enzyme that catalyzes the 2nd step of Ketogenesis.
Takes acetoacetyl-CoA and Acetyl-CoA and forms HMG-CoA
- HMG-CoA is a key intermediate in cholesterol biosynthesis
5
HMG-CoA lyase
Enzyme that catalyses the 3rd step of ketogenesis
Cleaves HMG CoA to form Acetoacetate and acetyl CoA
* conducted ONLY in liver*
6
(B) HDB dehydra
Enzyme that catalyses optional 4th reaction of Ketogenesis
Interchanges (b)-HDB and Acetoacetate
- going from acetoacetate -> (b)-HDB requires oxidation of NADH
- going from (b)-HDB -> acetoacetate requires reduction of NAD+
7
Ketone bodies are formed by what two molecules?
Acetoacetate and (b)-hydroxybutyrate
- acetoacetate can spontaneously form acetone
8
Advantage of ketone bodies over fatty acids
Ketone bodies are far more soluble and can move further in the body. (Fatty acid needs to use albumin as a transporter).
9
Ketolysis
Action of forming 2 acetyl CoA from ketone bodies
(Occurs in peripheral cell matrix)
10
BHB DHase
1st step of ketolysis
Converts (b) HDB into Acetoacetate and generates 1 NADH
* if ketone body arrives to peripheral cell as Acetoacetate already, this step is skipped*
11
Transferase
2nd step of ketolysis
Binds a succinyl group from succinyl-CoA to acetoacetate to form
AA-CoA and succinate
12
3-KA-CoA thiolase
4th step in ketolysis
Takes AA-CoA and generates 2 acetyl-CoA
13
How much ATP is formed from one (b)-HDB ketone body?
21.5 (transferase requires 1 ATP)
22.5-1 = 21.5
14
How much ATP is formed from 1 Acetoacetate ketone body?
19 (transferase requires 1 ATP)
20-1 = 19
15
Ketoacidosis is most common in what type of diabetes?
type 1 diabetes
16
What ketone body form is most favored under normal conditions?
b-HDB is more favored since NADH concentrations are favored over NAD+
17
