Flashcards in Amino Acid Metabolism Deck (25)
What are the sources of amino acids?
-Degradation of ingested protein
-Degradation of synthesized endogenous protein
What are the free amino acids used for?
-Degraded into nitrogen for release as urea
What enzymes are the most rapidly degraded?
Proteins most rapidly degraded are often ones
of the rate limiting step
What is nitrogen balance?
It is the intake and excretion of nitrogen and should be 0 in normal people.
When does positive nitrogen balance occur?
When does negative nitrogen balance occur?
What is the general pathway for urea formation from amino acid degradation?
Free amines -> Glutamate -> Ammonia OR Aspartate -> Urea
Where is urea synthesized?
What is the transamination reaction?
It is the transfer of the amine group on an amino acid to α-ketoglutarate which then generates glutamate
What is the cofactor necessary for the transaminase enzymes to carry out transamination?
What serves as the nitrogen reservoir in the body?
What do elevated levels of Alanine transaminase and/or Aspartate transaminase indicate?
They indicate liver tissue damage as the hepatocytes are lysing.
How is glutamate converted to aspartate?
How is glutamate converted to ammonia?
What is the primary regulated step of urea synthesis?
Formation of carbamoyl phosphate
What is the enzyme that catalyzes the regulated step of urea synthesis?
Carbamoyl phosphate synthetase I
What is the allosteric activator of carbamoyl phosphate synthetase I?
What enzyme converts arginine into urea?
Within the cell, where does the conversion of NH3 to carbomoyl phosphate and conversion to citrulline occur?
In the mitochondria. The rest of the urea cycle reactions occur in the cytosol.
What can occur with hyperammonemia?
What are glucogenic amino acids?
They can be converted to TCA cycle intermediates
or pyruvate for gluconeogensis
What are ketogenic amino acids?
They can be converted to acetyl CoA, acetoacetyl CoA, or acetoacetate
Name the ketogenic amino acids.
What occurs to amino acid and protein synthesis after a meal?
Protein synthesis will increase under the effect of insulin