Amino Acid Metabolism: Oxidation And Urea Flashcards
Name the 4 fates of Dietary Amino Acids
- Protein Synthesis
- Energy Production (Citric Acid Cycle)
- Biosynthesis
- Urea Excretion
Name the 3 drivers of Protein Oxidation
- Normal synthesis and degradation
- Protein rich diet
- Starvation or diabetes Mellitus
What does CCK do?
Stimulates zymogen release from the pancreas.
What does secretin do?
Stimulates the release of bicarbonate from the pancreas
Describe Pepsin
- It is a Protease
- Hydrolyzes Phe, Trp, and Tyr polypeptide bonds
What is stimulated by Gastrin Secretion?
- Causes chief cells to release Pepsinogen
2. HCL release (parietal cells)
How are cytoplasmic proteins broken down?
Tagged with ubiquitin and taken to proteosome
Lysosomes also break down proteins but not as much
What leads to Gastrin secretion?
Presence of Dietary proteins
Define Zymogen
An enzyme precursor that requires a biochemical change for activation, typically cleavage
In a low pH environment what happens to pepsinogen?
It is activated and becomes pepsin
Name 3 Pancreatic Zymogens and what they are cleaved to when they become activated
- Trypsinogen: Trypsin
- Chymotrypsinogen: chymotrypsin
- Procarboxypeptidase A and B: Carboxypeptidase A and B
What is the basic strategy for amino group catabolism in the liver?
Separate the amine group, leave the carbon chain
_________ is the source of most amino acids
Diet
Most amino acid catabolism occurs in _________
The liver
Name the 4 metabolically important amino acids
- Glutamate
- Glutamine
- Aspartate
- Alanine
What are the 4 Metabolically important amino acids used as?
- Amine group carriers
- Precursors and common metabolites
- Entry and exit molecules from the citric acid cycle
How are amine groups stabilized?
As urea or uric acid for excretion
Name two common amino acid catabolism reactions
- Transaminase Reactions
2. One-Carbon Transfers
What is PLP?
- Pyridoxal Phosphate
- It is a common coenzyme
- It is a carrier of amino groups
- Also Vitamin B6 (Essential Vitamin)
*From his slides it looks like it is particularly involved in Transaminase reactions
T/F Glutamine is Toxic
FALSE: it is non-toxic
How is Intra cellular ammonia buffered?
By converting glutamate to glutamine
Describe the urea cycle.
- Forms urea, a stable amine-rich molecule that can safely excrete nitrogen
- Requires enzymes within the mitochondria and cytoplasm
- There are 4 steps and 5 structural changes
- ATP-Dependent
- Ornithine is absolutely essential
What 3 molecules enter into first stages of urea cycle?
- Glutamine
- Glutamate
- Alanine
How is urea cycle regulated?
Two levels of regulation:
- Increased synthesis of
- Ornithine Transcarbomoylase
- Arginosuccinate synthetase
- Arginosuccinase
- Arginase
- Allosteric carbonyl phosphate synthetase 1 regulation
Name the 6 amino acids degraded to pyruvate
- Tryptophan
- Alanine
- Cysteine
- Serine
- Glycine
- Threonine
Name the 7 amino acids that are degraded to Acetyl-CoA
- Tryptophan
- Lysine
- Phenylalanine
- Tyrosine
- Leucine
- Isoleucine
- Threonine
Name the 5 amino acids degraded to alpha ketoglutarate
- Glutamate
- Glutamine
- Proline
- Arginine
- Histidine
Name the 4 amino acids degraded so Succinyl-CoA
- Methionine
- Isoleucine
- Valine
- Threonine
Name the 2 amino acids degraded to oxaloacetate
- Asparagine
2. Aspartate
Which amino acids can be converted to Acetoacetyl-CoA prior to forming Acetyl-CoA
- Leucine
- Lysine
- Phenylalanine
- Tryptophan
- Tyrosine
