Amino Acid Metabolism II Flashcards
(26 cards)
Describe the 3 pathways that are used to synthesize amino acids and the pathways that they are related to
3-phosphoglycerate, phosphoenolpyruvate and pyruvate from glycolysis
alpha-ketoglutarate and OAA from the TCA cycle
Ribose-5-phosphate, erythrose-5-phosphate from the pentose phosphate pathway
What are the 3 transamination reactions that occur in amino acid syntheses
- pyruvate/alanine by SGPT
- OAA/Aspartate by SGOT
- alpha ketoglutarate/glutamate exchange by Glutamate dehydrogenase
What are the fates of aspartate and what enzymes catalyzes these reactions?
- Asparagine synthetase changes the molecule into asparagine
- In other organisms, Aspartate can be turned into lysine, methionine and threonine
Describe the fate of glutamate?
Glutamine synthetase forms glutamine
What is the difference between synthetases and synthases?
Synthetases use ATP and synthases do not
Describe the regulation of glutamine synthesis
include what protein is involved
Adenylation (AMP addition) of the glutamine synthetase inactivates the enzyme
PII is a protein that binds to the adenylyl transferase, which causes adenylation of the enzyme (inactivation)
If a UMP is aded to the PII protein via uridylylation, and that binds to the adenylyl transferase, then the enzyme is deacetylated and the enzyme is activated
Why is it important that the cells are able to make glutamine from glutamate?
So that the excess NH4+ can be transported to the liver so that it can go through the urea cycle
What are the amino acids that can be formed from glutamate?
Glutamine, Proline, and Arginine
What are the amino acid derivatives of 3-phosphoglycerate?
- three reactions get to serine
- vitamins B6 and B12 help to remove the side chains from serine to make glycine
- serine can be converted through cysteine via a homocysteine
What is tyrosine a catabolic intermediate of?
Phenylalanine
Where are aromatic amino acids derived from? And which intermediates from this pathway make Histidine Tryptophan Phenylalanine Tyrosine
Aromatic amino acids come from the pentose phosphate pathway
Histidine comes from ribose-5-phosphate
tryptophan, phenylalanine and tyrosine come from Erythrose 4 phosphate combining with phosphoenolpyruvate to make choorismate
List and describe the amino acids that are synthesized from pyruvate?
Valine, Leucine, and Isoleucine
All have complex syntheses, exist to be incorporated into proteins, and are regulated by feedback inhibition
List the uses of amino acids
PAN
All Planning Parents Perform Active Sex Regularly—Now Pregnant
Activated Carriers Polypeptides Precursors Pigments Antioxidants Signaling Molecules Regulatory molecules Neurotransmitters Polyamines
What are the two central amino acids?
Glycine and Serine
Describe Heme
Acetate is converted to succinyl CoA prior to assembly
used for O2 transport
Heme is the main source of dietary iron
Describe the deficiencies in Heme synthesis
- What happens if there is a deficiency in a liver enzyme?
2/ A non-liver enzyme?
Porphyrias
- Sx related to pain and cardiac dysfunction
- non-liver; light sensitivity and altered skin pigmentation
Describe aliphatic molecules. What happens if you change the ring?
They absorb light via the pi-orbitals.
if you change the ring, you change the wavelength that is absorbed and changes the color transmitted (our eyes only see the transmitted)
What are the molecules that are derived from glutamate?
Glutathione-antioxidant
Polyamines-stabilize DNA
GABA- inhibitory neurotransmitter
List and describe the two arginine derived molecules
- NO: free radical that is from NOS; tied to G-protein signal cascade; nitroglycerin releases 3 equivalents of NO
- creatine phosphate: liver releases into the bloodstream; hydrolysis of phosphate from creatine releases same amount of energy as ATP
- uses SAM (methyl donor) a TON
What are the histidine derived molecules?
Histamine- secretion of HCl and pepsin in the stomach, vasodilation at the site of allergic reaction, neurotransmission
What kind of inhibition do antihistamines use?
Competitive inhibition
What are the tryptophan derived molecules?
serotonin; dictate insulin release from the pancreas, vasoconstriction and blood pressure regulator, intestinal contraction, NOS activation, and a precursor for melatonin
Describe the tyrosine-derived molecules
Catecholamines:
epinephrine (stress hormone) that causes vascular constriction, increase in blood pressure, and ceases inflammation
dopamine: increased leads to drug addiction and parkinson’s, decreased levels in parkinson’s and ADHD
Describe dark hair color
Eumelanins> phemolanins
