s2m1 biochem – amino acid metabolism – Flashcards
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Unlock answerswhat's the purpose of a transaminase in break down of amino acids? what other compound is needed? what Vitamin is needed? what is formed as a product? |
it's used to transfer the amino group also needs a-ketogluterate to take the amino group needs VitB6 (involved in the ping-pong mech) a ketoacid of the aa & a glutamate is formed as a product
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oxidation method of breaking down the glutamate formed from the transaminase rxn. what enzyme is used? where is this enzyme? what does it mean to see this enzyme in the blood? what are the byproducts? is this rxn reversible?
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glutamate dehydrogenase is used to oxidise the aa. done in the mitochondria severe liver damage -> will see this enzyme in the blood NADPH & NH4 are byproducts can reverse this rxn to form aa's (need alot of NADH+) |
how do we get rid of D-aa's? what's the significance of the enzyme used? what products can we make from it? where does this happen? ; |
using a d-amino acid oxidase makes the molecule achiral then with a transaminase can make an L-aa oxygen is used and hydrogen peroxide is produced thus this rxn occurs in the peroxisome to deal with it |
what produces D-serine in the brain? in response to what? what is the D-ser used for? what's it's pharmaceutical use? |
astrocytes in response to high glutamate concentration D-ser is used in long-term potentiation for neurons as a co-agonist for NMDA receptors pharm use: schizophrenia ; |
what does the body do with the amonia produced in aa metabolism? what's the first step in the urea cycle? where does this cycle take place? |
amonia enters the lysosome in which the acidic environment makes amonium which isn't watersoluble it's t/p to the liver where urea is made the first step is using the enzyme carbamoylphosphate synthetase 1 to make carbamoylphosphate (requires ATP) happens in the liver mitochondria |
what is done with carbamoylphosphate in the urea cycle? what disease is associated with this enzyme? |
the enzyme ornithine transcarbamoylase transfers it to Ornithine to make Citruline this enzyme can be defective, it's a x-linked recessive disease and is seen also in women in x-inactivation problems |
what is done with Citruline in the urea cycle? what enzyme? what additional amino acid is used? what's the product? where does this conversion happen? what's the disease associated with this enzyme? |
Argininosuccinate synthase uses Aspartate to make Argininosuccinate this happens in the liver cytosol Citrullinemia - desease if the enzyme is defective |
what happens to arginiosuccinate in the urea cycle? what's the enzyme used? what's the byproduct? what's the product? where does this happen? what disease is associated with this enzyme? what's the treatment for it? |
Arginiosuccinate lyase is used to convert it to Arginie Fumerate is a byproduct this happens in the liver cytosol Arginiosuccinate aciduria is a disease of a defective enzyme it's treated by giving Arginine & Ornitine
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what happens to arginine in the urea cycle? what enzyme is used? what's the product ; byproduct? where does this happen? if this enzyme is defective, what are the symptoms of the disease? ; |
Arginase makes Ornithine again (reused in the cycle), and also Urea is made happens in the liver cytosol defect: mental retardation ;spastic quadriplegia; ; ; |
give a summary of the urea cycle what are the symptoms of inherited;diseases that affect the enzymes in this cycle? |
NH4 + stuff + Aspartate = stuff + Fumerate + Urea disease symptoms: hyperammonemia Reye-syndrome (encephalopathy - fatal) aversion against protein rich foods feeding problems ; vomiting ataxia, lethargy, coma, death ; ; |
problems in urea cycle as a result of liver failure / cirrhosis 2 causes? 4 symptoms? Rx? ; |
caused by alcoholism or viral hepatits symptoms: ataxia slurred speach tremor (asterixis) mental derangements RX: no alcohol, less protein in diet replace aa with their a-ketoacids or 2 pharmacuticals that can react w aa's to then be excreted in urine 1. benzoate + Gly -> hippurate 2. phenylacetate + Gln -> phenylacetyl-Gln
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regulation of urea cycle
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breakdown of aa's give alot of Glutamate Glu -; converted to N-acetyl glutamate this allosterically activates carbamoyl phosphate synthetase 1 |
essential aa's 3 basic, 2 lions, what does meth do? the vallet tipped who? |
3 basic: Arginine, Histadine, Lysine 2 lions: Leucine, Isoleucine Meth puts you on a Tryp: methionine, tryptophan Phenylalanine, Valine, Threonine the VALlet tipped THREe PHingers-to-ALAN: Valine, Threonine, Phenylalanine |
what are the two uses of the carbon chains in amino acids? problem with excess ketones? |
glucogenic - make glucose ketogenic - make ketone bodies excess - ketoacidosis -> diuresis
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what's the atkins diet? how does the brain get energy? what's the problem with making ketone bodies? result of diuresis? what are the confounding factors? |
low carb/high protein+fat glucose needed for brain thus body breaks down fat & protein (loss of lean body mass) to much ketonebodies -> ketoacidosis leads to diuresis: loss of water & minerals (short term weight loss) confounding = environmental & congenital people w/ these issues on atkins diets can succumb to shock, coma, death
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how is alanine metabolised? what enzyme is used? what's the product? what can this be used for? what's the clinical use of this enzyme?
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glutamate-pyruvate transaminase (GPT) or alanine aminotransferase (ALT) transaminases alanine to make pyruvate it's used in gluconeogenesis clinical: hepatocyte damage -; release enzyme into blood |
| what are the two pathways to break down serine? |
1. gluconeogenesis path - uses alot of energy ; 2. serine dehydratase -; breaks down serine directly to pyruvate (used in gluconeogenesis) |
what's the breakdown pathway of aspartate & asparagine? what is the product used for? |
asparagine can be converted to aspartate by asparaginase or the other way around by asparagine synthetase aspartate is used to make oxaloacetate for the citric acid cycle by Aspartate Glutamate Transaminase this enzyme, also called AST (aspartate transaminase) is in heart/skeletal muscle/liver -> problem -> see AST in blood |
| how is glutamine & glutamate metabolised? |
glutamine is converted to glutamate via glutaminase glutamate is converted to oxogluterate which is used in the citric-acid cycle the enzyme used is oxogluterate amino transferase |
how is glycine metabolised? 4 ways with two diseases? |
1. Bacteria converts it to Trimethylamine 2. in the peroxisome it's converted to oxalate - can become kidney stones if Calcium is bound 3. glycine cleavage enzyme can make amonium ; CO2 -a problem in this enzyme -; hyperglycinemia = fatal or severe mental deficiency 4. Ser-hydroxymethyl transferase can make serine out of it |
how is threonine metabolized? ; |
1. made into glycine 2. made into pyruvate 3. made into Succinyl-CoA |
in folate metabolism, what is sulfanilimide used for? ; |
it looks like the para-amino-benzoic acid in folic acid.; normally folate is used in DNA nucleotide synthesis sulfanilimide disrupts this process, thus slows down bacterial cell division this gives our immune system time to kill the bacteria |
| what is trimethoprim used for, regarding the folate metabolism pathway? |
the first step of the pathway is for folate to be converted by the enzyme Dihydrofolate Reductase Trimethoprim inhibits this enzyme to kill bacterial cell division |
| what is methotrexate used for, regarding the folate metabolism pathway? |
| anti cancer - it inhibits the dihydrofolate reductase enzyme, thus prevents cell division |
methionine metabolism; what are the 1st two steps? byproducts? what is the fate of Homocystine? what disease can cause a buildup of homocystine? |
met -; SAM (use 2 ATP's & add adenosyl) -> SAH (by cleaving a methyl group) -> remove adenosyl to make Homocystine Homocystine can be converted back into Methionine by using VitB12 A Folate dificiency will block this step thus get a buildup -> vascular disease
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breakdown pathway of homocystine (from Methionine metabolism) converted to what? what are the reactants needed for this? malfunction of this causes what? symptoms? Rx? final breakdown products of Met? |
Serine + VitB6 + Cystathione synthase is used to convert it to Castathione Malfunction = Homocystineuria accumulation of homocystine -> mental retardation, lens dislocation, bone elongation, osteoperosis RX - Met restriction mega dose of B6 Final products = Propionyl-CoA & Pyruvate, both used in gluconeogenesis |
what is methylmalonyl-CoA synthase used for? if it's blocked? what's used instead? what is not a cure for this problem? |
it uses malonic acid in FA synthesis if it's blocked it uses methylmalonic acid instead folate is not a treatment |
Oasthouse disease what's defective? what happens to the Methionine? what symptoms? |
intestinal Met-transporter deficient so bacteria converts the Met to α-hydroxybutyrate which is excreted by the kidney urine smells like oushouse (hobs in beer) white hair, diarrhea, convulsions, mental retardation, tachypnia |
methylmalonic aciduria which pathway is blocked? |
| Propionyl-CoA conversion to Succinyl-CoA |
Maple Syrup Urine disease what pathway is blocked? |
branch chain a-ketoacid dehydrogenase is blocked thus the conversion from Isoleucine to Tiglyl-CoA is blocked disease is auto recessive mental deficiency optic atrophy ataxia AHDS elevated branch chain aa's in serum |
what are the branch chain amino acids? what's the first step of their metabolism? where does this happen? where does the rest happen? |
Val, Ile, Leu transamination happens in muscle, the rest in liver |
what's the first step of Phe (phenyl alanine) metabolism? what's the disease associated with it? symptoms Rx?
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Phe gets hydroxylated by Phenylalanine Hydroxylase to make Tyrosine Phenylketouria results when this enzyme is defective Mental retardation, seizures, spasticity Rx with Phe restricted diet |
Tyrosinaenemia type II what enzyme deficient? |
tyrosine aminotransferase affects brain, eyes, skin tyrosine can't be converted to hydroxyphenyl pyruvate |
tyrosineanemia type III which enzyme is deficient? symptoms |
p-hydroxyphenyl pyruvate oxidase mild mental retard ; ataxia |
tyrosineanemia type I what enzyme is deficient? ; |
Fumarylacetoacetate hydrolase cabbage-like smell from FA's liver & kidney failure liver cancer |
hawkinsinuria symptom? what's excreted? mode of inheritance? Rx? |
acidemia hawkinsin is excreted autosomal dominant restrict tyrosine in diet |
hyperlysineanemia what enzyme is deficient get a buildup of what? symptoms? |
Saccharopine is deficient it's what converts Lysine to Saccharopine get buildup of lysine physical & mental retard |
what causes histadineanemia? what does it convert? Dx: what's the final product of histadine break down? ; |
histidinase doesn't function it converts histadine into urocanate Dx: lack of urocanate in sweat final product of histidine breakdown is glutamate |
in what tissues are these aa's metabolised? Glu + Gln Val, Ile, Leu other AA's |
Glu + Gln catabolized in the intestinal mucosa Val, Ile, Leu transaminated in muscle, ketoacid then catabolized to liver other AA catabolized in the liver |
| what's the overall fate of Alanine? |
transaminated in the liver pyruvate used in gluconeogensis ammonia is t/p fr muscle to liver |
what happens to Glycine in the kidney? what about in the intestine? |
Kidney: metabolic acidosis -; glutaminase ; glutamate dehydrogenase forms NH3 a-ketogluterate -; gluconeogenesis ; Intestine: catabolism |
cystinuria what is the problem? result? |
| Cystine re-uptake in kidney;leads to kidney stones |
cystinosis what's the problem? result? symptoms? Rx? |
defect in cystine t/p out of lysosome leads to cystine crystals in lysosomes blindness rickets kidney failure hypogonadism poor growth Rx: cysteamine slows progress |
what's Hartnup's disease?
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t/p for large aa's defect Trp deficiency results in higher requirement for niacin to avoid pellagra |
what are 2 uses for polyamines? what two diseases is it associated with? so how would you treat it? |
they're (-) charged so used in DNA packing also in NMDA & AMPA receptor in the brain polyamine hypersynthesis: seen in cancer & sleeping sickness Rx: target the Ornithine decarboxylase (1st step in polyamine synth) |
