Amino Acid Degradation & Urea Cycle Flashcards
Two Sources of Amino Acids:
- diet
- degradation of defective/unnecessary cellular proteins
Two Reasons Proteins May Be Defective:
- errors in translation
- oxidative damage
First 2 Priority Use of Amino Acids
- protein synthesis
- nucleotide synthesis
If the needs for protein synthesis and nucleotide synthesis have been met, what happens to amino acids?
They are degraded into carbon skeletons for metabolism. The nitrogen is removed from the amino acids and excreted as urea.
Are amino acids stored for later use?
No.
NH4+
ammonium
ammonium
NH4+
Describe the Basic Structure of an Amino Acid
An Amino Group (NH3+),
a Carboxyl Group (COO-),
and an R Group all attached to a C
(an alpha-H is also attached to the C)
What what does Alanine become when the Amino Group is removed?
pyruvate
Amino Group
NH3+
Carboxyl Group
COO-
What does alpha-ketoglutarate become when an alpha-amino group is added?
glutamate
What does Asapartate become when the amino group is removed?
oxaloacetate
What is formed from the oxidative deamination of glutamate?
alpha-ketoglutarate
What is the excreted form of NH4+ called?
Urea
What is the significance of glutamate dehydrogenase?
It assists Nitrogen entry and exit from biochemical systems
What does glutamate dehydrogenase use for reducing power?
NADH or NADPH
What does ATP and GTP do to glutamate dehydrogenase?
alloseterically inhibits it
What does ADP and GDP do to glutamate dehydrogenase?
allosterically activates it
When is the oxidation of amino acids the fastest?
when the energy charge in the cell is low
The amino groups of which two amino acids can be converted directly into ammonium?
serine
threonine
What are the 3 Branched Chain Amino Acids?
Valine
Leucine
Isoleucine
Which amino acids can the liver not deaminate?
The branched chain amino acids:
valine, leucine, & isoleucine
