Lecture 3 (2A) - Amino Acid Breakdown Flashcards
Nitrogen –> urea,
but where do the carbon skeletons go?
degrade to
- citric acid cycle
- their precursors
~10 - 15 % of all metabolic energy
Amino acid breakdown creates
new amino acids
• amino acids integrate with each other, 1 may provide for another
20 amino acids
varied breakdown pathways
Glucogenic
breakdown to glucose precursors (to CA cycle)
- pyruvate
- α-ketoglutarate
- succinyl CoA
- fumarate
- oxaloacetate
Ketogenic
breakdown to ketone bodies (to CA cycle indirectly)
• acetyl CoA (acetoacetyl CoA)
Number of glucogenic amino acids
13
Number of ketogenic amino acids
2
Both glucogenic and ketogenic amino acids
5
- Ile
- Thr
- Phe
- Tyr
- Trp
Breakdown of carbon bodies (carbon backbone)
- to pyruvate
- to oxaloacetate
- to α-ketoglutarate
- to succinyl CoA
- to acetoacetyl Coa
- to fumarate
Breakdown of carbon bodies
to pyruvate
- alanine
- cysteine
- glycine
- serine
- threonine
- include tryptophan –> alanine (–> pyruvate)
Breakdown of carbon bodies
to oxaloacetate
- asparagine, aspartate
- asparagine –> aspartate (–> oxaloacetate)
Breakdown of carbon bodies
to α-ketoglutarate
- arginine
- glutamate
- glutamine
- histidine
- proline
- all to glutamate first, then to α-ketoglutarate
- NH3 off first, then all C + 1N into glutamate
Breakdown of carbon bodies
to succinyl CoA
(associated with the citric acid cycle)
- isoleucine
- methionine
- threonine
- valine
- C feature all the way to succinyl CoA (propionyl CoA = odd chain fatty acid)
Breakdown of carbon bodies
to acetoacetyl CoA
- leucine
- lysine
- phenylalanine
- tryptophan
- tyrosine
Breakdown of carbon bodies
to acetyl CoA
- isoleucine
- leucine
- tryptophan
Fate of carbon skeletons of amino acids
Pyruvate formation from amino acids
α-ketoglutarate formation from amino acids
Succinyl CoA formation
Full succinyl-CoA formation
