Term
What is hyperuremia and what are its effects? |
|
Definition
In hyperuremia, the body's equilibrium is shifted towards making more glutamate and glutamine to get rid of an NH4+ buildup (highly toxic). Glutamine is the only amino acid that can cross the blood-brain barrier, so the brain is still affected even though the body is protected from the NH4. Newborns with this urea cycle defect become lethargic, vomit, then comatose. MNEMONIC: GLUTAMINE is MEAN to the brain. |
|
|
Term
| What do glutamate and glutamine have to do with Amino Acid synthesis? |
|
Definition
They act as a Nitrogen donor. They receive their N during synthesis directly from NH4+. Ex: Asparagine is formed using a N from Glutamate. |
|
|
Term
| Recite PVT TIM HLL, the essential AA mnemonic. |
|
Definition
| Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Leucine, and Lysine. |
|
|
Term
| What are the six key Amino Acid synthesis precursors? |
|
Definition
1. OAA 2. Pyruvate 3. PEP 4. 3-Phosphoglycerate 5. alpha-Ketogluterate 6. Ribose 5-Phosphate |
|
|
Term
| ALT/AST are key liver enzymes. What do they do? |
|
Definition
They are both transaminases used in alanine and aspartate synthesis. Pyruvate->ALT OAA->AST |
|
|
Term
| In the course of amino acid synthesis, can free ammonia be found anywhere in the course of the reactions? |
|
Definition
| No. Sources such as glutamine bind nitrogen and release it directly into enzymes that contain the NH4 and transfer it safely. |
|
|
Term
| Name the two precursors that can be used to synthesize proline. |
|
Definition
Glutamate OR Arginine. BONUS: This reaction features a spontaneous cyclization reaction (no enzyme) that creates proline. |
|
|
Term
| Ornithine is an intermediate in the creation of Proline from Arginine. Can this reaction pathway be reversed? |
|
Definition
Yes, though it requires high levels of proline. Still, Arginine can be formed from ornithine via the urea cycle. Ornithine->Citrulline->Arginine BONUS: Ornithine is in that sense synthetized from Proline. It can also be created from Glutamate, though this happens rarely. |
|
|
Term
Serine is a precursor for what Amino Acid? BONUS: Is there an allosteric mechanism in place during the synthesis of Serine? |
|
Definition
Glycine is created from Serine. BONUS: Yes. Serine undergoes a transamination reaction that is allosterically inhibited by high serine levels. |
|
|
Term
Tetrahydrofolate is a key enzyme made from Folic Acid. What is its function? Hint: It's reliant on oxidation states. |
|
Definition
THF, in it's intermediate methylene (-CH2-) state, acts as a 1C donor in a variety of reactions. In its reduced state, it is methyl; in it's oxidized, it is -CHO or -CH= |
|
|
Term
| During methanol poisoning, high doses of ethanol are given to competitively inhibit the -OH receptors. Folate is also given. Why? |
|
Definition
| Folate pushes the equilibrium of one of the intermediates of methanol metabolism, Formate, inhibiting the reaction. |
|
|
Term
| Where does the vast majority (95%) of methylenetetrahydrofolate come from? |
|
Definition
Serine to Glycine synthesis. Serine + THF -> Glycine + methylene-THF BONUS: Glycine can also be synthesized from CO2, NH4, and methylene-THF. |
|
|
Term
| What is the role of SAM (S-Adenylmethionine) in AA synthesis pathways? |
|
Definition
| It is a highly reactive methyl group donor. |
|
|
Term
| What are the two biosynthetic reaction that require Vitamin B12? |
|
Definition
1. Regeneration of Methionine from methyl-THF (happens in the Active Methyl Cycle) 2. Succinyl-CoA synthesis BONUS: The active methyl cycle can only regenerate Methionine that has been modified; it does not synthesize it. MNEMONIC: B12 and Meth will both make your hands tingle; that Succs! |
|
|
Term
Vitamin B12 contains what heavy metal as a cofactor? Hint: The clinical name of B12 is cobalamin. |
|
Definition
| Co3+ is used (similar setup to Fe in Hg). BONUS: The cobalt is attached to various sidechains (-X sidebar on slide). These are donated by the cobalt during various reactions. |
|
|
Term
| Methionine (regenerated via the active methyl cycle, uses SAM) is a key precursor to what amino acid? |
|
Definition
Cysteine. Homocysteine is a key part of the active methyl cycle, of which methionine is a part. Homocysteine will react with Serine to eventually form Cysteine. |
|
|
