Block 2 Lecture 4 -- Amino Acid Synthesis Flashcards
What are the essential amino acids?
1) Phe
2) Val
3) Thr
4) Try
5) Ile
6) Met
7) His
8) Arg
9) Leu
10) Lys
Which amino acids are synthesized from glycolysis intermediates?
1) Ser
2) Gly
3) Cys
4) Ala
What amino acids are synthesized from TCA intermediates?
1) Arg
2) Asp
3) Asn
4) Glu
5) Gln
6) Pro
What amino acids do not have transamination pairs?
1) Lys
2) Pro
3) Thr
Which non-essential amino acid is not derived from glycolysis/TCA?
Tyr (from the essential Phe)
What is the TA pair for Glu?
a-KG
What is the TA pair for Asp?
OAA
What is the TA pair for Ala?
Pyruvate
What is the TA pair for Gly?
glyoxylate
What is the TA pair for ornithine?
Glu-5-Semialdehyde
How can serine be synthesized?
1) 3-phosphoserine phosphatase – from 3-PG, direct product of glucose via 3-PGDH
2) serine hydroxymethyltransferase – from glycine (THF)
What compounds can serine synthesize?
1) serine dehydratase = pyruvate
2) + homocysteine –> cystathionine –> cysteine
3) serine hydroxymethyltransferase = glycine via THF
how is serine synthesis induced?
1) 3-PGDH induction
2) release of phosphoserine phosophatase feedback inhibition
How is glycine synthesized?
1) Serine hydroxymethyltransferase
2) Thr aldolase
How is glycine degraded?
1) GCC donates carbon to FH4, produces CO2 + NH4
2) D-amino-oxidase oxidizes to glyoxylate
3) TA to glyoxylate with Ala/pyruvate
What is the cofactor in GCC?
NAD & FH4
What is the cofactor in Thr aldolase?
PLP
How is cysteine synthesized?
1) cystathionine synthase then cystathionase
What reactions does cysteine do?
1) desulfhydrase
- - donates NH3 to Glu
- - carbons become pyruvate
- - sulfate to urine
What is the cofactor in cystathionine synthase?
PLP
What reaction does cystathionine synthase catalyze?
Ser + Homocysteine –> Cystathionine
What is the cofactor in the cystathionase reaction?
PLP
What reaction does cystathionase catalyze?
Cystathionine + H2O –> a-KB + cysteine + NH4
How is alanine produced?
transamination with pyruvate – especially in muscle
How is Glu produced?
1) TA with a-KG
2) from Gln (Glutaminase)
3) from FIGLU (His & THF)
What reactions does Glu take part in?
1) Gln synthase
2) TA
3) Glu DH (urea cycle)
4) reductase & phosphorylation –> Glu-5-SA
How is Pro synthesized?
1) spontaneous cyclization of G5SA
2) reduction (FAD/NAD)
What is the co-factor in GluDH?
NAD
How is glyoxylate degraded?
1) oxidized to oxalate
…or….
2) to a-KG with TPP as cofactor
What functional group is produced when G5SA cyclizes?
Schiff base/imine
Where does proline synthesis occur in the cell?
1) Glu phosphorylation –> G5SA in mitochondria
2) G5SA reduced to Pro in cytosol
How is arginine produced?
1) G5SH TA to ornithine, enters urea cycle
2) Arginase produces Arg
Where does TA occur with G5SH?
- *on the side chain
- - an oddity
What happens when ornithine is in excess?
G5SA increases
Glu increases
What amino acids are synthesized form G5SA
Proline & Arginine
What is a sign of folate deficiency related to His metabolism?
FIGLU would be found in urine
How is aspartate synthesized?
1) TA with OAA (PLP)
2) Asn-ase (hydrolytic non-oxidative deamination)
How is Asn synthesized?
1) Asn synthetase (requires ATP & Gln)
What cofactors does Asn synthetase require?
1) ATP
2) Gln –> Glu
