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21 Cards in this Set
- Front
- Back
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How is Nitrogen removed from AA's?
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1. Transamination: uses pyridoxal phosphate (PLP)
2. Oxidative deamination: may also use PLP (e.g., serine dehydratase) |
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What is NAG?
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N-acetylglutamate NAG is an activator for Carbamoyl Phosphate Synthetase to create Carbamoyl Phosphate
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How is NAG synthesized?
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NAG is formed from acetylCoA and glutamate, catalyzed by N-acetylglutamate synthase (activated by arginine)
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List The Enzymes of the Urea Cycle
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Ornithine Transcarbamoylase (OTC)
Argininosuccinate Synthetase (AS) Argininosuccinase = Argininosuccinate Lyase (AL) Arginase |
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What is the action of Ornithine Transcarbamoylase (OTC)?
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OTC catalyzes the transfer of a carbamoyl group to ornithine to form citrulline.
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What is the action of Argininosuccinate Synthetase AS?
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Catalyzes the formation of argininosuccinate from citrulline and aspartate
Occurs in cytosol ATP-dependent |
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What is the action of Argininosuccinase/ Argininosuccinate Lyase AL?
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Cleaves argininosuccinate into arginine and fumarate.
Results in the transfer of an amino group from aspartate to arginine |
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How are the Urea Cycle with the TCA cycle linked?
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via Fumarate and Aspartate
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What is the action of Arginase?
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Cleaves arginine to urea and ornithine,
returns to beginning of the cycle. |
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What happens when there is a defect in urea synthesis?
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Any defect in urea synthesis results in hyperammonemia, due to the inability to remove nitrogens produced during amino acid catabolism
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Defects known at every step of the urea cycle T/F?
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True
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Which urea cycle enzyme deficiency is x-linked?
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OTC X-linked, the rest Autosomal recessive
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What are some Clinical Symptoms of Urea Cycle Disorders ?
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Neonatal - irritability, vomiting, lethargy, seizures, hypotonia, coma, death.
Childhood - hyperactive, refusal of meat, vomiting, lethargy, delirium, coma, and death. Adults - stroke-like symptoms, lethargy, delirium; can lead to brain damage, coma, and death |
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How are urea cycle disorders treated?
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1.Restriction of protein in diet - allow essential amino acid intake, but reduce ammonia formation
2.Medications that provide alternate pathways for ammonia removal 3.Research undergoing for Gene therapy for treatment... |
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How would you treat CPS and OTC Deficiencies?
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provide alternate routes of nitrogen excretion
Sodium benzoate and Sodium phenylacetate: Ammonul brand name via IV |
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How would you treat a NAG Synthase Deficiency?
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Treat with carbamoyl glutamate
-Analog of N-acetylglutamate -Able to activate carbamoyl phosphate synthetase |
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How would you treat Argininosuccinate Synthetase Deficiency (Citrullinemia)?
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Treat with excess arginine for protein synthesis
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How would you treat Argininosuccinase Deficiency?
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Treat with excess arginine and protein restriction
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How would you treat Arginase Deficiency?
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Treatment: diet excluding arginine but including essential amino acids
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Glucogenic AA's can be broken down to form which intermediates?
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Pyruvate, Fumarate, a-ketoglutarate, Succinyl CoA, Oxaloacetate
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Ketogenic AA's can be broken down to form which intermediates?
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Acetyl CoA
Acetoacetyl CoA |
