Amino Acid Metabolism - Catabolism Flashcards
How do the different enzymes of the small intestine function?
Enteropeptidase -> Cleaves trypsinogen
Aminopeptidase -> Exopeptidases which chew from N-terminus
Dipeptidase -> Brak apart dipeptides
What determines the rate of ubiquitination of proteins destined for the proteosome?
Identity of the terminal N Amino Acids
What are the possible outcomes of ubiquitination?
- Degradation
- Recycling
- Factor recruitment
- Change of localization or activity
- Disruption of interactions
What is the general structure of the Proteosome?
- ATPase
- 20S Catalytic domain
- 19S regulatory domain
What can happen to amino acids after being degraded by the proteosome?
- Dispose of Nitrogen via Urea Cycle
- Make a new protein
- Repurpose Carbon Skeleton
What is the process of deamination of amino acids?
Most follow 2 step Enzymatic reaction:
- Aminotransferase
- Glutamare dehydrogenase
- Pyridoxal phophate is coenzyme
** Exception is Serine and Threonine which use Dehydratase
What is the role of ALT/SGPT?
Catalyzes interconversion of Alanine/Pyruvate
What is the role of AST/SGOT?
- Catalyzes interconvention of Aspartate and Oxaloacetate
What is the substrate/process used to transport NH4+ from most tissues to the Liver?
Glutamate + NH4+ –> Glutamine —-> Glutamate + NH4+ (in Liver)
How is NH4+ transported from muscle tissue to the liver?
NH4+ –> Glutamate -> Pyruvate –> Alanine -> Glu (In liver) -> NH4+ (In liver)
Describe the first step of the Urea Cycle.
Carbomoyl phosphate Synthetase I (CSPI) combines CO2 (from TCA) and NH3 to make Carbamoyl Phosphate using 2 ATP.
*Comited step
**NAG is an allosteric activator
Describe the second step of the Urea cycle.
Ornithine is transprted ino mt to combine with Carbamoyl Phosphate to form Citrulline. Citrulline is exported to the cytoplasm.
Describe step 3 of the urea cycle.
Aspartate donates an NH3 to citralline to form arginine and fumarate.
*Uses 2 ATP
Describe the last step of the Urea cycle.
Addition of water cuases release of urea from Arginine. Ornithine is regenerated.
*Fumarate created in last step regenerated to OAA using TCA.
What are the different fates of protein carbon skeletons?
Glucogenic -> Gluconeogenesis
Ketogenic -> Ketone Bodies
Both Glucogenic and Ketogenic
