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22 Cards in this Set

  • Front
  • Back
Glutamate (Glu) is the precursor or product of what five amino acids?
1. Glutamine
2. Histidine
3. Proline
4. Arginine
5. ??????
What are the enzymes and substrates involved in the interconversion of Glutamine and Glutamate?
Glutamate --> Glutamine
*glutamine synthetase

Glutamine --> Glutamate

Reactions are irreversible and can keep pools of each separate unless enzymes are present.
Glutaminase is the enzyme for what reaction?
Glutamine --> Glutamate
Glutamine Synthetase is the enzyme for what reaction?
Glutamate --> Glutamine
In Asparagine Synthesis, what is the N donor?
Glutamine's amide group (asparagine synthatase)
What are the enzymes of Aspartate synthesis and degradation?
Aspartate --> Asparagine
*asparagine synthtase

Asparagine --> Aspartate

Irreversible reactions
Aspartate and Asparagine have a one step relationship like what two other amino acids?
Glutamate and Glutamine
*Glutamate to alpha-KG *freely reversible
*key role in interconversion of ammonia and glutamate
*not PLP dependent
*NAD/NADH dependent
*glutamate as a resevoir compound for N
*a way for the body to get free ammonia for urea or reverse reaction to get rid of it
What cofacter is required for all AA decarboxylases and aminotransferases?
How is GABA made?
From glutamate, and an aa decarboylase that uses PLP as a cofactor.
How do you synthesize Proline?
Proline can be derived from Glutamate.

Glutamate -> Glutamate semialdehyde (GSH) -> /\'-Pyrroline 5-carboxylate (P5C) -> Proline
How do you synthesize Arginine?
From Glutamate

Glutamate -> Glutamate Semialdehyde (GSH) -> Ornithine -> Arginine
Arginine to Ornithine produces what by product? Where is this reaction abundant?
Urea is a by product. So a vast amount of arginine is made in the liver for making urea. Arginase reaction only happens in the liver.
How are polyamines made and what are they used for?
Polyamines are made from decarboxylated ornithine (which can be made from arginine, glutamate). The amines can form longer compounds.

Polyamines have positive charges that bind to DNA.
What is the Nitric Oxide precursor?
Arginine (made in a single step using O2)
When arginine goes to ornithine, what does it give off?
What three amino acids are used in creatine synthesis?
1. Glycine
2. Amidino group of arginine
3. Methyl group of methionine if the form of SAM
Glutathione (GSH)is made of what 3 amino acids?

How are they bound?
1. Glycine
2. Cysteine
3. Glutamate

They are not bound through a peptide bound but through a carboxylate tail so they cannot be digested by normal peptidases.
What is the function of glutathione?
*stabilizes cells
*can detoxify peroxides by forming GSSG
*reacts with xenobiotices through sulfhydryl group to detoxify
Describe Glutathione-based Transport.
*participates in aa transport system
*active in liver and KIDNEY
*if flood system can get a lot of glutathione breakdown but have to reassemble to keep it going
*needs to be reassembled
Why do xenobiotics (like acetaminophen) pose a problem for glutathione?

What problem may occur?

How can it be treated?
Glutathione needs to be regenerated in order for it to detoxify other substances. When it reacts, its adducts lose Glu and Gly portions and is acetylated to form mercapturic acids, which is excreted. So now the system is without cysteine. If too much xenobiotics are taken in, the system has to wait for glutathione to be regenerated in order to do other functions.

The xenobiotic (acetominophen) becomes a toxin (NAPQI)when cellular supply of glutathione is used up. Liver failure can ensue, particularly for individuals with existing liver damage.

N-acetyl cystein is a remedy to replace the excreted cysteine.
What is mercapturic acid?
Excretion compound formed when glutathione reacts w/xenobiotics. It is excretable from the kidney.