Biochemistry - Metabolism - Proteins and stuff Flashcards
Which amino acids are “essential” amino acids?
Glucogenic: Methionine, Valine, Histidine
Glucogenic/ketogenic: Isoleucine, Phenylalanine, Threonine, Tryptophan
Ketogenic: Leucine, Lysine
Which amino acids are acidic?
Aspartic acid, Glutamic acid. (Neg at body pH).
Which amino acids are basic?
Arginine, Lysine, Histidine.
Which amino acids are required during periods of growth?
Arg and His
Which amino acids are in histones?
Arg and Lys.
What is the purpose of the urea cycle?
In order for the carbon skeletons of amino acids to be broken down and used as energy the nitrogen must be removed; the urea cycle converts nitrogen into urea so it can be excreted.
What is the basic structure of an amino acid?
H2N-CH-COOH with an R group coming off the middle C. The R group distinguishes the amino acid.
What is the structure of carbamoyl phosphate?
CO2 + NH3 –(ATP)–> H2N-COO-phosphate
What is required for the conversion of CO2 + NH3 to carbamoyl phosphate?
N-acetylglumatate, 2ATP + carbamoyl phosphate synthetase
What is the structure of urea?
H2N-CO-NH2
What is the role of alanine/glutamate in taking nitrogen from amino acid to urea?
In Muscle: Amino acid (NH3) —> glutamate (NH3) –> Alanine (NH3). Alanine can be transported to Liver where it can become pyruvate/glucose, donating NH3 back to glutamate, which becomes urea.
What is alpha-ketoglutarate critical for?
1) Picks up ammonia from aspartate to become glutamate
2) Intermediate in TCA.
What does hyperammonemia deplete and lead to?
Leads to depletion of alpha-ketoglutarate, leading to inhibition of TCA.
What are the symptoms of hyperammonemia?
tremor (asterixis), slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision
What are the treatments for hyperammonemia?
1) limit protein in diet
2) lactulose acidifies the GI tract and tracts NH4+ for excretion
3) Rifaximin decreases colonic ammoniagenic bacteria
4) Benzoate/phenylbutyrate bing amino acid and lead to excretion, can decrease ammonia levels.