Week 9 - Unit 2 Flashcards
Intermediates of the TCA cycle are used for :
- heme synthesis
- Gluconeogenesis
- Fatty acid synthesis
- AA synthesis
One turn of the TCA cycle makes:
1- GTP
3- NADH
1- FADH2
What are the 4 things that can all generate acetyl CoA for the TCA cycle?
- fatty acid- palmitate
- ketone body- acetoacetate
- pyruvate
- Ethanol
Fatty acids and keytone bodies are ______ to acetyl-CoA
oxidized
AA _____ can be converted to pyruvate and then oxidized to Acetyl-CoA
Alanine
What enzyme converts pyruvate to acetyl-CoA at the end of glycolysis
Pyruvate dehydrogenase complex
True or false:
conversion of pyruvate to acetyl-CoA will transfer a H to NAD to make NADH (first in TCA pathway)
True
What are the inhibitors of pyruvate dehydrogenase?
- NADH (its own byproduct)
2. Acetyl-CoA (product)
What are the activators of Pyruvate Dehydrogenase ?
Calcium
ADP
The Pyruvate Dehydrogenase complex is part of the family of _____ ____ -_______
Alpha-keto-acid dehydrogenases
What are the three main a-keto acid dehydrogenases associated with TCA cycle ?
- Pyruvate Dehydrogenase
- Alpha Keto-glutarate dehydrogenase
- Branched chain AA dehydrogenase (MSUD)
What are the three subunits of of the Pyruvate dehydrogenase complex and what do they bind?
- E1= binds TPP
- E2= binds lipoate
- E3 = binds FAD
What is the E1 subunit on pyruvate dehydrogenase called?
Pyruvate decarboxylase subunit
-binds Thyamine Pyrophosphate (2 P groups )
What is the E2 subunit on pyruvate dehydrogenase called?
Transcylase subunit
-binds lipoate
What is the E3 subunit called on the pyruvate dehydrogenase called?
Dihydrolipoyl dehydrogenase
-binds FAD
What is the bond called that is created when pyruvate is converted to Acetyl CoA ?
High energy Thioester bond
O=C~SCoA
When you convert Pyruvate to Acetyl CoA what 2 things are created as byproducts?
NAD to NADH
CoASH to CO2
The creation of the high energy thioester bond of Acetyl CoA is coupled with what?
Reduction of NAD to NADH
In step one of Pyruvate to Acetyl CoA, what occurs?
Pyruvate loses CO2 when A-keto acid DH acts on it and takes the acetyl group
What is step oneafter the CO2 is lost from pyruvate?
Remaining 2 carbons are covalently bonded to Thyamine Pyrophosphate
-done by PDH
What is step 2 after TPP is bound to Pyruvate that lost CO2
Requires lipomide
-2 Carbon unit is transfered and attaches to lipoic acid
What happens after the 2 carbon unit (acetyl group) is transferred from the E1 unit with TPP (alpha-keto acid DH) to the E2 group of lipoic acid ?
- Acetyl group attached to thioester in Lipoic acid ( attached to trans Ac enzyme)
- -TPP regenerated for use again in step 1
3.Dihydrolipoyl transacetylase intermediate formed
What is step 3 after the
Dihydrolipoyl transacetylase is formed?
Acetyl is attached to CoA group to make Acetyl-CoA (still high energy thioester bond)
PDH is used again to attach the acetyl to CoA
What happens after the Acetyl-CoA is formed to the Transacetylase enzyme ?
Oxidized by FAD
-FAD is reduced to FADH2 which is then simultaneously oxidized by NAD as soon as FADH2 is made