ketogenic amino acids

[justforgotfrag]

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Hi, I found this online:

Ketogenic amino acids: Their carbon skeletons are degraded to acetyl-CoA or acetoacetate. Acetyl CoA, and its precursor acetoacetate, cannot yield net production of oxaloacetate, the precursor for the gluconeogenesis pathway. For every 2-C acetyl residue entering Krebs Cycle, two carbon atoms leave as CO2.

For example: lysine and leucine are both ketogenic. What I dont really get is how losing 2 carbons cannot yield the net product of oxaloacetate in the citric acid cycle? Can someone explain why?

 

[typicalindian]

Hi, I found this online:

Ketogenic amino acids: Their carbon skeletons are degraded to acetyl-CoA or acetoacetate. Acetyl CoA, and its precursor acetoacetate, cannot yield net production of oxaloacetate, the precursor for the gluconeogenesis pathway. For every 2-C acetyl residue entering Krebs Cycle, two carbon atoms leave as CO2.

For example: lysine and leucine are both ketogenic. What I dont really get is how losing 2 carbons cannot yield the net product of oxaloacetate in the citric acid cycle? Can someone explain why?

no

 

[Ashley1989]

no

You should've just posted picture, typicalindian 😉

 

[typicalindian]

You should've just posted picture, typicalindian

you should have just bippidy the boppidity and booped the boop.

 

[Ashley1989]

you should have just bippidy the boppidity and booped the boop.

🙁 so mean

 

[typicalindian]

🙁 so mean

That's a compliment. Ask good ol bill

 

[sparkleys]

TCA Cycle: Pyruvate -> Oxaloacetate
Pyruvate (3 Carbons) -> Acetyl CoA (2 Carbons) via Pyruvate Dehydrogenase Complex (Irreversible)

That means Acetyl CoA cannot be made into pyruvate due to a loss of a carbon. Can't put it back on. This is also why Fatty Acids that yield Acetyl CoA cannot be made into glucose.

 

[DAPI]

For a more serious answer 🙄

Net oxaloacetate = total final oxaloacetate - starting oxaloacetate.

So start with 1 Oxa and add 1 Acetyl CoA to run the krebs cycle. When it finishes you get 1 Oxa, 2 CO2, and some other stuff (NADH, FADH2, GTP, etc.). Therefore you have 0 net Oxa.

Also:

 

[justforgotfrag]

Thanks! I got it now ;D

 

[alpharez]

If you're looking for some net OAA, I got a friend named Pyruvate Carboxylase.

 

[MangoPlant]

What class is this for? Biochemistry?

 

[Ashley1989]

That's a compliment. Ask good ol bill

:-0 whaaaaa exactly are you implying here, Typical

 

[alpharez]

What class is this for? Biochemistry?

Yeah most likely.

 

[487806]

:-0 whaaaaa exactly are you implying here, Typical

It's a typical joke for a typical member likely from a typical movie or typical show. But I didn't get it either, so I guess we are both atypical.