Amino Acids Flashcards
Tryptophan
Aromatic
Leucine
Branched
Isoleucine
Branched
Which two amino acids are ketogenic?
Leucine and lysine
Which four amino acids are both glucogenic and ketogenic?
Tyrosine, isoleucine, phenylalanine, and tryptophan.
What are the two intracellular pathways for protein degradation?
- Ubiquination and degradation in the proteasome
2. Degradation in lysosomes
What are the two nitrogen sources that enter the urea cycle?
Free ammonia from breakdown of an amino acid and from aspartate.
Which amino acid produces NO?
Arginine
Which AAs contain sulfur?
Cysteine and methionine
SAM is a precursor for what?
Homocysteine
Which amino acids are aromatic?
Tryptophan, tyrosine, phenylalanine
What is the Keq of transamination reactions?
1 - concentration dependent
ALT catalyzes which reaction?
Alanine + alphaketoglutarate -> pyruvate + glutamate
AST catalyzes which reaction?
Aspartate + alphaketoglutarate -> OAA + glutamate
What is PLP’s role in transamination?
Coenzyme to aminotransferases. Holds the N nearby.
PLP is a derivative of what?
Vit B6
Write out the overall reaction of the urea cycle
3ATP+HCO3+NH4+aspartate -> 2ADP+AMP+2Pi+PPi+fumarate+urea
What stimulates glutamate dehydrogenase and what inhibits it?
(+) ADP and GDP
(-) ATP and GTP
Write out the overall reaction of the urea cycle
3ATP+HCO3+NH4+aspartate -> 2ADP+AMP+2Pi+PPi+fumarate+urea
Which disease is associated with a deficiency in alpha ketoacid dehydrogenase complex?
MSUD
Which enzyme decarboxylates branched chain AAs?
alpha ketoacid dehydrogenase complex
Which disease is associated with a deficiency in alpha ketoacid dehydrogenase complex?
MSUD
Tryptophan metabolism results in the formation of what?
Niacin, serotonin, melotonin
Phenylalanine metabolism results in the formation of what?
Tyrosine, L-dopa, dopamine, melanin, NE, and epi
Glycine metabolism results in the formation of what?
Porphyrin and heme
Glutamate metabolism results in the formation of what?
GABA and glutathione
Arginine metabolism results in the formation of what?
NO, creatine phosphate, and urea
What can cysteine do?
Form disulfide bridges that change protein conformation
How can ammonia be transported to the liver for urea cycle?
Glutamine synthase can convert glutamate to glutamine to be transported to the liver.
What does muscle use to transport nitrogen?
Alanine instead of glutamine - due to buildup of pyruvate in muscle which can be converted to alanine with ALT
Which amino acid is associated with GSH?
Cysteine
SAM is a breakdown product of which AA?
Methionine
What are the starting and ending points of purine biosynthesis?
Ribose 5P -> IMP
What are the two key steps of purine biosynthesis?
PRPP synthetase and GPPA (glutamine phosphoribosyl pyrophosphate aminotransferase)
What are the activators and inhibitors of PRPP synthetase?
(+) Pi
-) purines, AMP, GMP, IMP (end-product inhibition
What are the activators and inhibitors of GPPA?
(+) PRPP
(-) AMP, GMP, IMP
What are the sources of atoms for purine synthesis?
Glutamine, glycine, aspartate, THF, CO2
What are the starting and ending points of pyrimidine synthesis?
2ATP + CO2 + glutamine -> UMP
What is the key enzymatic step of pyrimidine synthesis?
CPS II
What are the activators and inhibitors of CPS II?
(+) ATP, PRPP
(-) UTP
What are the sources of atoms for pyrimidine synthesis?
CO2, glutamine, aspartate, ribose sugar added last
What is a major difference between pyrimidine and purine biosynthesis?
In purine synthesis, the base is built onto the sugar. In pyrimidine synthesis, the complete base is added onto the sugar at the end.
Which enzyme converts RNA to DNA?
Ribonucleotide reductase
What is an inhibitor of ribonucleotide reductase?
dATP
On which phosphate form does ribonucleotide reductase act on exclusively?
Di-phosphate form
What does thymine break down to?
Succinyl-CoA
What does cytosine break down to?
Malonyl-CoA
What does uracil break down to?
Acetyl-Coa