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29 Cards in this Set

  • Front
  • Back
characteristics of protein
don't store them
broken down in liver
aa's used for energy (15% of need)- starv, DM, exercise
(via pyruvate DH to ACoA)
general method for protein catabolism
get carbon skeletons
-c skels carried by alpha KG
-glutamate can clean up NH3
-glutamine & alph KG into mito join TCA
-branched aa's need special enzyme

releases ammonia
-carried to liver (via alanine- NH3+pyruvate & glutamine)
- goes to urea cycle
enzymes used in aa catabolism
aminotransferase/transaminase (eg AST & ALT)
-use B6 (PLP activated B6)
steps in aa metabolism for carbon skeletons
amino acid to alpha Ketoacid
(alpha KGrate takes amonia & further processed to glutamate)
Alpha KG to glutamate
(NH3 into hepato, bicarb, generate glutamine)
glutamate to glutamine via synthetase (ATP)

alpha keto acid will be processed (SAM, THF or Biotin)

uses transaminase/transferase
role of glutamine in aa catabolism
used to clean up NH3
delivers it to liver

LOTS in brain, makes GABA
glutaminase
converts glutamine to glutamate (NH to urea cycle)

releases NH (complexes w/HCO3)
role of alanine in aa catabolism
indicates burning protein for energy

glucose alanine cycle (not Cori)
-ala from musc to liver
-generate pyruvate & glutamate (via ALT)
- gluconeogenesis for energy
methyl donors
SAM, THF, Biotin
for 1 C transfers
glucogenic aa's
can become pyruvate (or go into TCA)

isoleucine, phenylalanine, tyrosine, triptyphan
ketogenic aa's
can become ACoA

leucine & lysine
branched chain aa's
takes two steps to get to TCA
-aminotransferase
-BCAK Dh complex
(branched chain alpha
ketoacid)
-get AcylCoA derivative


maple syrup urine dz is problem with BCAK Dh complex
-CoASH, NAD, CO2, TPP* (like PD gets ACoA for TCA/FA synth)

build up alph Ketoacids of
leucine, isoleucine & valine

*TPP= thiamine pyrophosphate
catabolism of phenylalanine
-hydroxylase to tyrosine
-continues to fumarate & acetoacetate for TCA
(or tyrosine derived products)
-BH4 dependent enzyme

PKU is problem w/hydroxylase
Phe builds up
acumulate aromatic metabolites
(phenllactate, phenylpyruvate, phenylacetyl-CoA)
HPA
hyperphenylalanimia

eg PKU

auto recessive
defic of Phe Hydroxylase


severe MR, sx's, hyperactive
tyroseinemias (for board)
I- build up fumarate
II- accum tyrosine
III-accum hydroxphenylpyruvate
fate of glutamine in aa metabolism
TCA & Urea cycle
enzyme to form glutamine from glutamate
glutamine synthetase
location & function of glutamate dehydrogenase
in mito
produce alpha KG
(for urea cycle)
to aspartate (from OAA)

gives NH4 for carbamoyl phosphate
location & function of CPS 1
in mito
poduce carbamoyl phosphate (for urea cycle)
adds NH4 to CO (from bicarb) & PO (from ATP)
location of urea cycle
mitochondria
-glutamate & NH4 & HC03
-carbomyl phosphate
-ornithine

cytoplasm
-ornithine (in to mito)
-citruline (out from mito)
-aspartate
-argininosuccinate
-arginine
-(Ornithine)
fate of citruline after it leaves mito
(from ornithine minus P)
combines w/aspartate
(from glutamate & g DH & OAA in mito)


argininosuccinate synthetase
has 2 N groups
arginine succinate synthetase
in urea cycle
makes argininosuccinate
uses 2 ATP equiv's
has 2 NH groups
argininosuccinate lyase
gives fumarate & arginine
(from argininosuccinate)
arginase
splits urea off
(from arginine)
gives ornithine back
regulation of urea cycle
short term
-allosteric N acetylglutamate (inhibits)

long term
-rate of synth of enzymes
products of urea cycle
urea, 2 ADP, AMP, 4 Pi
(uses 2 NH4 & 3 ATP & 1 HCO3)
possible reasons for NH toxicity (in brain)
decreases Glu & GABA
osmotic edema
ATP depletion
fate of arginino succinate (from urea cycle)
argininosuccinate=
arginine (for urea cycle)
fumarate (to malate for TCA)

aspartate from TCA to UA
-uses citruline
tx for ammonia toxicity
(b/c def in enzymes)
limit aa intake
(replace w/alpha k acids)

decrease bacterial production

remove excess ammonia
(aromatic acids-benzoate, phenylbutyrate)
replace missing intermeds
benzoate & phenylbutyrate
aromatic acids to remove NH3