Term
| The major process for removing nitrogen from amino acids is? |
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Definition
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Term
| All amino acids can undergo transamination reactions except for? |
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Definition
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Term
| What is a required cofactor for a transamination reaction and what is it derived from? |
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Definition
| pyridoxal phosphate derived from Vit B6 (pyridoxine) |
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Term
| What is formed during amino acid degradation, is toxic and can cause mental retardation, coma and death? |
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Definition
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Term
| What cycle is responsible for tranforming ammonia, so it can be eliminated via the kidneys? |
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Definition
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Term
| Most amino acids can transfer there nitrogen group to? |
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Definition
| alpha-ketoglutarate via a transamination rxn |
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Term
| These three amino acids result in a direct deamination, resulting in free ammonia being formed? |
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Definition
| Serine(Ser,S), Threonine (Thr, T), and Histidine (His, H) |
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Term
| Which organ has the job of detoxifying ammonia from the body? |
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Definition
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Term
| Ammonia equivalents are transported from outlying tissues such as the brain and muscle via? |
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Definition
mainly- glutamine and glutamate
special circumstances- alanine |
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Term
| Remove amino groups from amino acids to alpha-ketoglutarate with the aid of B6 |
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Definition
| Transaminases- it forms an alpha-keto acid and glutamate |
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Term
| Whose function is to produce and degrade glutamine? |
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Definition
| glutamine synthetase and glutaminase |
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Term
| This enzyme deals with free ammonia by transferring it to a glutamate with the help of ATP? |
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Definition
| Glutamine Synthetase- the resulting products are glutamine and ADP, glutamine goes to the liver, where it is dealt with further |
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Term
| This catalyzes the removal of the amide nitrogen from glutamine in order to form glutamate and free ammonia. |
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Definition
| Glutaminase- found throughout body, but most prevalent in the liver and kidney |
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Term
| This freely reversible reaction takes glutamate + NAD(P)+ and makes alpha-ketoglutarate + NH3 + NAD(P)H. |
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Definition
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Term
| What is an activator for Glutamate Dehydrogenase(for either direction)? |
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Definition
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Term
| What is an inhibitor for Glutamate Dehydrogenase(for either direction)? |
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Definition
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Term
| These four enzymes when combined together allow for the removal of free ammonia from the peripheral tissues, where it can safely be transferred via glutamate and glutamine to the liver, where free ammonia can be reformed and packaged and excreted. |
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Definition
1) Transaminases
2) Glutamine Synthetase
3) Glutaminase
4) GDH |
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Term
| Small peptides or amino acids are absorbed by what in the intestinal lumen? |
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Definition
| enterocyte via sodium symporWhaters |
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Term
| What is the primary energy source for the intestinal cells and the kidney? |
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Definition
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Term
| Protein turnover occurs in all cells and this can produced during turnover? |
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Definition
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Term
| What tissue type is the primary site of metabolism of branched chain amino acids? |
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Definition
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Term
| After a protein meal, excess NH3 is carried via pyruvate in the form of? |
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Definition
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Term
| Alanine goes to the liver and undergoes what rxn? |
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Definition
| It is converted back to pyruvate via a transamination rxn, finally pyruvate will go through gluconeogenesis and leave the liver as glucose. |
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Term
| When can NH3 be found in the urine? |
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Definition
| When energy levels are low or under amino acid excess(high protein diet). Liver can't handle the excess glutamine and it is sent over to the kidney where glutaminase works to make glutamate and free NH3 from glutamine, |
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Term
| What is found in the mitochondria and required to create a precursor for the urea cycle. It takes free NH3 and CO2 plus water and @ ATP to make what? |
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Definition
| Carbamoyl Phosphate Synthetase I forms Carbamoyl-P + 2 ADP + Pi |
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Term
| What two enzymes important to the urea cycle are found in mitochondria? |
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Definition
CPS I (Carbamoyl Phosphate Synthetase I)
GDH (Glutamate Dehydrogenase) |
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Term
| What enzyme takes carbamoyl-P and ornithine and makes citrulline and Pi? |
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Definition
| Ornithine Transcarbamoylase |
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Term
| What condensation reaction with aspartate and citrulline requires ATP and it makes argininosuccinate. |
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Definition
| This occurs in the cytoplasm of the cell and the enzyme is Argininosuccinate Synthetase |
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Term
| How does citrulline transported to the cytoplasm? |
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Definition
| In an exchange transport with ornithine |
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Term
| What rxn releases fumarate and arginine from Argininosuccinate? |
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Definition
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Term
| What is the source of the two nitrogens found in urea? |
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Definition
| free ammonia (in the form of carbamoyl-phosphate) and aspartate |
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Term
| What enzyme splits arginine into urea and ornithine? |
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Definition
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Term
| How many ATP is used per urea cycle? |
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Definition
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Term
| The generation of this, links the urea and TCA cycle? |
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Definition
| fumarate (generated in the urea cycle) |
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Term
| Ornithine is formed through a series of rxns that start with? |
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Definition
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Term
| Long-term adaptation in the urea cycle results in? |
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Definition
| A three-fold increase in the urea cycle enzymes |
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Term
| Also in starvation when amino acid degradation is high, the urea cycle enzymes can be increased another? |
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Definition
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Term
| CPS-1 is positively regulated by? |
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Definition
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Term
| What enzymes takes ACCoA and Glutamate and makes N-AcGlu(N-Acetylglutamate)? |
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Definition
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Term
| N-AcGlu Synthetase is activated by? |
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Definition
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Term
| Is there any inhibitors of the urea cycle? |
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Definition
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Term
| Defects in any enzyme in the urea cycle results in? |
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Definition
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Term
| What will indicate a problem in the urea cycle? |
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Definition
| Excess ammonia (hyperammonemia) or elevated glutamine levels |
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Term
| Individuals with CPS-1 defects results in elevations of |
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Definition
| NH3 and lethargy and vomiting |
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Term
| What is the most common defect in the urea cycle? |
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Definition
| OTC deficiency- It is X-linked in addition to having hyperammonemia, pts will have increased level of ornithine and carbamoyl-P |
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Term
| Defects in this lead to increases in citrulline levels (citrullinemia) along with hyperammonemia and orotic aciduria |
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Definition
| Defect in argininosuccinate synthetase (can be seen in newborns and there is also a late onset version/less severe) |
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Term
| Defects in this enzyme (second most common problem) hyperammonemia is not as common in these pts. Instead excess ammonia is secreted as argininosuccinate and these pts will require supplemental arginine in their diet. |
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Definition
| Defects in Argininosuccinate Lyase |
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Term
| This defect leads to elevated levels of arginine (not a common disorder) in both blood and urine-pt symptoms vary but can include convulsions and spastically |
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Definition
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Term
| What two things are given to pts with defects in the urea cycle? |
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Definition
1)Benzoate racts with glycine and is secreted as Hipurate (1 nitrogen secreted)
2) Phenyl-acetate- combines with glutamate and is secreted as Phenylacetyl Glutamine (2 nitrogens secreted) |
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