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29 Cards in this Set
- Front
- Back
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characteristics of protein
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don't store them
broken down in liver aa's used for energy (15% of need)- starv, DM, exercise (via pyruvate DH to ACoA) |
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general method for protein catabolism
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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 |
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enzymes used in aa catabolism
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aminotransferase/transaminase (eg AST & ALT)
-use B6 (PLP activated B6) |
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steps in aa metabolism for carbon skeletons
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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 |
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role of glutamine in aa catabolism
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used to clean up NH3
delivers it to liver LOTS in brain, makes GABA |
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glutaminase
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converts glutamine to glutamate (NH to urea cycle)
releases NH (complexes w/HCO3) |
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role of alanine in aa catabolism
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indicates burning protein for energy
glucose alanine cycle (not Cori) -ala from musc to liver -generate pyruvate & glutamate (via ALT) - gluconeogenesis for energy |
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methyl donors
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SAM, THF, Biotin
for 1 C transfers |
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glucogenic aa's
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can become pyruvate (or go into TCA)
isoleucine, phenylalanine, tyrosine, triptyphan |
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ketogenic aa's
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can become ACoA
leucine & lysine |
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branched chain aa's
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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 |
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catabolism of phenylalanine
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-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) |
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HPA
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hyperphenylalanimia
eg PKU auto recessive defic of Phe Hydroxylase severe MR, sx's, hyperactive |
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tyroseinemias (for board)
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I- build up fumarate
II- accum tyrosine III-accum hydroxphenylpyruvate |
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fate of glutamine in aa metabolism
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TCA & Urea cycle
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enzyme to form glutamine from glutamate
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glutamine synthetase
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location & function of glutamate dehydrogenase
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in mito
produce alpha KG (for urea cycle) to aspartate (from OAA) gives NH4 for carbamoyl phosphate |
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location & function of CPS 1
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in mito
poduce carbamoyl phosphate (for urea cycle) adds NH4 to CO (from bicarb) & PO (from ATP) |
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location of urea cycle
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mitochondria
-glutamate & NH4 & HC03 -carbomyl phosphate -ornithine cytoplasm -ornithine (in to mito) -citruline (out from mito) -aspartate -argininosuccinate -arginine -(Ornithine) |
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fate of citruline after it leaves mito
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(from ornithine minus P)
combines w/aspartate (from glutamate & g DH & OAA in mito) argininosuccinate synthetase has 2 N groups |
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arginine succinate synthetase
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in urea cycle
makes argininosuccinate uses 2 ATP equiv's has 2 NH groups |
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argininosuccinate lyase
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gives fumarate & arginine
(from argininosuccinate) |
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arginase
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splits urea off
(from arginine) gives ornithine back |
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regulation of urea cycle
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short term
-allosteric N acetylglutamate (inhibits) long term -rate of synth of enzymes |
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products of urea cycle
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urea, 2 ADP, AMP, 4 Pi
(uses 2 NH4 & 3 ATP & 1 HCO3) |
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possible reasons for NH toxicity (in brain)
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decreases Glu & GABA
osmotic edema ATP depletion |
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fate of arginino succinate (from urea cycle)
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argininosuccinate=
arginine (for urea cycle) fumarate (to malate for TCA) aspartate from TCA to UA -uses citruline |
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tx for ammonia toxicity
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(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 |
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benzoate & phenylbutyrate
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aromatic acids to remove NH3
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