Term
| Give two causes of ammonia toxicity. |
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Definition
| 1) Liver failure. (Rx = low protein diet) 2) Inborn errors of metabolism. |
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Term
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Definition
| Glutamate (5C) loses CO2 to become Gamma-Amino Butyric Acid (4C). |
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Term
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Definition
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Term
| What AA's are ONLY ketogenic? What do they give rise to? |
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Definition
| Leucine (to HMG CoA) and Lysine (to Acetyl CoA). |
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Term
| What AA's are BOTH ketogenic and glucogenic? What do they give rise to? |
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Definition
| Isoleucine (to Acetyl CoA or Propoionyl CoA), Phenylalanine (to Acetoacetate or Fumarate), Tyrosine (to Acetoacetate or Fumarate), Tryptophan (to Acetyl CoA or Serine to Pyruvate), and Threonine (to Acetyl CoA or Glycine to Serine to Pyruvate) |
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Term
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Definition
| Ala + A-KG --> Pyr + Glutamate (ALT, PLP) |
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Term
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Definition
| Major p'way: Ser --> Pyr + NH4+ (Serine Dehydratase, PLP) |
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Term
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Definition
| Cys --> Pyr + H2S (Desulfhydrase in many steps, PLP) |
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Term
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Definition
| Both reversible: 1) Gly --> Ser (Serine Hydroxymethyl Transferase (5,10-methylene THF, PLP)) 2) Gly --> CO2 + NH4+ (Glycine Cleavage Enzyme/Glycine Synthase, THF, NAD+) |
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Term
| Degradation of Threonine? |
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Definition
| Thr --> Aminoacetone + CO2 (Threonine Dehydrogenase, NAD+) --> Gly + Acetyl CoA (Threonine Dehydrogenase, CoA). RXN is irreversible (Threonine is essential). |
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Term
| How are Aspartate and Asparagine degraded? |
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Definition
| 1) Asn + H20 --> Asp (Aspariginase). 2) Asp + A-KG --> Glutamate + OAA (4C) (AST, PLP) |
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Term
| What AA's are converted to Glutamate? |
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Definition
| Histidine (non-reversible; req. THF), Proline, Glutamine (Glutaminase), and Arginine (has non-reversible step (essential AA); also goes to Urea Cycle). Glutamate then converts to A=KG and enters TCA. |
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Term
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Definition
| Valine is a branched-chain AA. It requires a BCKA Dehydrogenase after it is been transaminated into a KA. Valine enters as Propionyl CoA --> Succinyl CoA (Gluconeogenic) |
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Term
| How is isoleucine degraded? |
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Definition
| Isoleucine is a branched-chain AA. It requires a BCKA Dehydrogenase after it has been transaminated into a KA. Isoleucine yields both Acetyl CoA (Ketogenic) and Propionyl CoA à Succinyl CoA (Gluconeogenic) |
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Term
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Definition
| Leucine is a branched-chain AA. It requires BCKA Dehydrogenase after it has been transaminated into a KA. Leucine converts to Acetoacetate and Acetyl CoA (Ketogenic). |
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Term
| What is Maple Syrup Urine Disease? |
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Definition
| Deficiency in BCKA Dehydrogenases yields build up in Ketoacids from BCAA's. BCKA Dehydrogenase is similar to pyruvate dehydrogenase and uses lipoamine, TPP, FAD, and NAD as cofactors. Rx: Thiamine (T in TPP). |
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Term
| How are Tyrosine and Phenylalanine degraded? |
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Definition
| Phe --> Tyr (Phenylalanine Hydroxylase, BH4) --> Fum + Acetoacetic Acid (Homogentisate Oxidase) |
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Term
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Definition
| Genetic disorder whereby patients cannot catalyze hydroxylation of Phenylalanine (to Tyr). Rx: Low Phe diet. (Atypical PKA: Deficiency is in dihydrobiopterin reductase (converts BH2 to BH4 with NADH2) |
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Term
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Definition
| Deficient Homogentisate Oxidase. Buildup of homogentisic acid. Urine darkens upon exposure to air. Arthritis later in life. |
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Term
| How is Tryptophan degraded? |
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Definition
| It's usually conserved and converted to niacin, seratonin, melatonin, and NAD+. Deficiency = Pellagra. |
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Term
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Definition
| Converted to Acetyl CoA (Ketogenic). |
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Term
| How is Alanine generated? |
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Definition
| From pyr (transamination) |
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Term
| How is Aspartate generated? |
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Definition
| From OAA (transamination) |
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Term
| How is Glutamate generated? |
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Definition
| Reductive amination of A-KG or by glutamate dehydrogenase (from His, Arg, Pro). |
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Term
| How is Glutamine generated? |
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Definition
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Term
| How is Arginine generated? |
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Definition
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Term
| How is Proline generated? |
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Definition
| Two steps from Glutamate. |
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Term
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Definition
| From 3-PG (from glycolysis) or from Glycine |
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Term
| How is Glycine generated? |
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Definition
| 3-PG (glycolysis) --> Serine --> Glycine (hydroxymethyltransferase, PLP, BH4) |
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Term
| How is Cysteine generated? |
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Definition
| From Serine and Methionine. (Essential without Methionine in diet.) |
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Term
| How is Tyrosine generated? |
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Definition
| From Phenylalanine. (Tyr essential without Phe in diet. Also essential in patients with PKU.) |
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