Acetyl CoA and the CAC Flashcards
What is the metabolic fuel for the CAC?
acetyl CoA
acetate+coenzyme A =?
acetyl CoA
What 3 things make up coenzyme A?
- AMP with extra P group attached to ribose
- phosphorylated pantothentic acid (B5)
- mercaptoethyalimine
The reduced thiol (SH) in coASH can react with what to form what type of linkages?
react with carboxyl groups to form thioester linkages
Acetyl Coa can be formed from what 3 things? Acetyl Coa in turn can be used for what 4 processes?
carbs, lipids, amino acids
- CAC
- Fatty acid biosynthesis: TAG, Phospholipids
- Ketone Body formation
- Cholesterol biosynthesis: steroid hormones, bile acids, vit D
Biochemical reaction for oxidative decarboxylation of pyruvate?
Pyruvate + NAD+ + COASH –> PDH –> acetyl CoA + NADH + CO2 + H+
What 3 enzymes make up the PDH complex?
pyruvate decarboxylate: (Ena) dihydrolipoyl transacetylase (Enb) dihydrolipoyl DH (EnC)
What is vitamin B1?
thiamine
Where is the PDH complex located?
mitochondrial matrix
Where is the pyruvate from glycolysis generated?
in the cytosol
Where is the protein translocase for pyruvate located?
in the inner mit membrane
What are the 5 coenzymes for the PDH complex?
2 soluble: Coa and NAD+
3 tighly bond: TPP, lipoamide, FAD
What 4 B vits are required for PDH complex?
- Pantothenic acid (B5) - CoAsh
- Thiamin (B1) - TPP
- Niacin (B3)- NAD+
- Riboflavin (B2) (FAD)
What is riboflavin required for?
it is B2.. and FAD needs it
What is B2?
riboflavin
What B vitamin does NAD+ require?
niacin
Draw out the steps of the CAC!!! anddddd GO :)
:)
What 3 steps produce NADH?
- isocitrate + NAD+ –> isocit DH –> aKG + NADH+CO2+H
- aKG + CoASH+ NAD+ –> aKG DH –> succinyl-COA + CO2 + NADH+ H+
- malate + NAD+ –> mal DH –> OAA + NADH + H
What CAC step produces GTP?
- succinyl-COA + GDP –> succinyl COA synthetase –> succinate + GTP
What step in the CAC utilizes water?
- Fumurate + H20 –> fumarase –> malate
CO2 is produced in what 2 steps?
- isocitrate + NAD+ –> iso DH –> aKG + NADH + CO2 + H+
4. aKG + CoASH + NAD+ –> akg DH –> sucinnyl COA + NADH + H+ CO2
What step in the CAC produces FADH?
- succinate + FAD –> suc DH –> fumurate + FADH2
How many ATP are produced from the CAC?
12 ATP total
11 from Oxidative Phos:
3 NADH produced –> 3 x 3 ATP : 9 ATP
1 FADH2 produced –> 1 x 2 ATP: 2 ATP
1 ATP from substrate-level Phosphorylation
How many ATPS can be produced from each molecule of Pyruvate?
15 ATP
How many ATPS can be formed from each glucose molecule?
30 ATP
Citrate can be utilized to make what?
acetyl coa –> fatty acids: sterols
AKG can make what?
Glutamate –> amino acids (purines)
Succinyl-CoA can make what?
porphyrins (hemes, cytochromes)
malate can be used to make what?
Pyruvate–> alanine
OAA can make what?
Phosphoenolpyruvate –> Glucose
Aspartate –> AA, urea, purines, pyrimidines
Aspartate can be made from what CAC product?
OAA
What CAC product can make glutamate?
a-KG
What CAC product can indirectly make alanine?
malate
What 2 anaplerotic reactions are used to replenish OAA?
- Pyruvate + ATP + HCO3 –> pyr carboxylase –> OAA
2. Glutamate + NAHP” –> Glutamate DH–>a-KG + NADPH + NH4
Pyruvate carboxylase requires what B vitamin?
biotin!!
The PDH complex is inactivated by what process and what 4 things?
inactivated via phosphorylation (kinase)
acetyl-CoA
NADH
ATP
fatty acids
The PDH complex is activated by what process and what 4 things?
activated via dephosphorylation
pyruvate
NAD+
ADP
CoASH
What 2 enzymes are regulated in the CAC?
isocitrate DH
a-KG DH
Isocitrate DH is regulated by what?
+ by ADP
- NADH
a-KG is regulated by what?
- succinyl-Coa and NADH
Although a-KG complex is similar the the PDH complex is it not regulated by what processes?
phos/dephos
PDH deficiency?
defects cause chronic lactic acidosis; this is because the pyruvate produced is reduced by NADH to lactate
Thiamine deficiency?
B1 deficiency: required by both PDH and aKG;
elderly and the poor are susceptible; and alcoholics; loss of appetite, constipation, nausea, fatigue, mental depression and peripheral neuropathy; and wernicke korsakoff syndrome
Beri-beri?
polished rice diets; dry: no fluid retention
wet: edema and cardiac failure
-beri beri can present with serum lactic acidemia
What will result from CAC deficiencies?
serum lactic acidemia
What are 3 ketone bodies that are formed in fasted and starvation in uncontrolled type 1 diabetes?
- acetoacetate
- b-hydroxybutyrate
- acetone