amino acid degradation Flashcards
pyruvate family
alanine, serine, glycine
alanine breakdown
alanine to pyruvate
E: alanine aminotransferase (ALT)
alpha-KG to glutamate
serine breakdown
serine to pyruvate releases unstable aminoacrylate E: serine dehydratase (SDH) releases H2O requires B6 PLP complex (vit B6)
glycine breakdown 2 pathways
1) glycine to serine, then to pyruvate
2) glycine degraded directly
glycine to serine
glycine to serine
E: serine hydroxymethyltransferase (SHMT)
THF to N5, N10 - Methylene THF + H2O
requires B6
glycine cleavage system
Glycine breakdown
E: glycine oxidase in reverse
requires PLP and lipoic acid
what is PLP?
active form of vit B6
asparagine breakdown
1) asparagine to aspartate E: asparaginase releases NH4+ 2) aspartate + alpha-KG to glutamate + oxaloacetate E: aspartate aminotransferase (AST)
which 2 amino acids yield oxaloacetate?
Aspartate (Asp-D) and Asparagine (Asn-N)
alpha-KG family
glutamate and glutamine
glutamine breakdown
1) glutamine to glutamate E: glutaminase H2O to NH4+ 2) Glutamate to alpha-KG E: glutamate dehydrogenase (GDH) NADP+ to NADPH + NH4+
glutamate breakdown
glutamate to alpha-KG
E: glutamate dehydrogenase (GDH)
NADP+ to NADPH + NH4+
succinyl-CoA family
Methionine, Isoleucine, and Valine
arginine and proline
get broken down, they’re being processed
methionine breakdown
methionine can produce cysteine then propionyl-CoA
SAM is used as a methyl donor
BCAT
branched-chain amino acid aminotransferase
leucine breakdown
1) leucine to alpha-ketoisocaproate E: BCAT alpha-KG to G 2) BCKDH, fatty acid oxidation to become acetoacetate and acetyl-CoA
phenylalanine/tyrosine
1) phenylalanine to tyrosine
E: phenylalanine-4-monooxygenase
2) tyrosine to rho-hydroxy-phenylpyruvate
E: tyrosine transaminase
alpha-KG to Glu
then dioxygenases to acetoacetate + fumarate
tyrosine synthesis
from phenylalanine
cysteine synthesis
from methionine
glutmate
from glutamine and vice versa
serine and glycine role
1 carbon donation (they form pyruvate!)
amino acid products
1) physiologically active amines
2) glutathione (management of S-S bonds)
3) heme
4) NAD+
glutamate produces
GABA and Histamine
tyrosine produces
Catecholamines
EX: Dopa, Dopamine, Norepinephrine –> (uses SAM) Epinephrine
glycine produces
heme
