Amino acid metabolism Flashcards
what do amino acids make?
protein
amino acid general structure
amine group, carboxylic acid group, unique side chain
essential amino acids
obtained from dietary sources of protein
HILKMFWVT
non-essential amino acids
made in our body
ANYPRDSCEQG
after a large meal
protein broken into amino acids
amino acids used as building blocks in protein synthesis
why do cells need to make use of amino acids?
ammonia (amine group) can become toxic if it is freed and builds up
how do we get rid of ammonia?
ammonia must be removed, sent to liver to be metabolized into a less toxic molec: urea
what enzyme transfer amino group from amino acids to keto acids
transaminases/aminotransferases
transamination reactions
reversible
can go in either direction using the same enzyme
what do transamination reactions require?
pyridoxine (Vitamin B6) as a cofactor
alanine transamination
in a muscle cell
alanine transaminase (ALT) switches amino group on alanine with oxygen on alpha-ketoglutarate
results in pyruvate (with oxygen group) and glutamate (with amino group)
what do we do with pyruvate? (option 1)
pyruvate dehydrogenase converts pyruvate to acetyl-CoA
acetyl-CoA can enter citric acid cycle
what do we do with pyruvate? (option 2)
1) lactate dehydrogenase converts pyruvate to lactate which then travels to the liver
gluconeogenesis or glycolysis
make acetyl-CoA and ATP
why is glutamate unique?
it is the only amino acid that doesn’t have to transfer its amine group to another molecule
how does glutamate get away with not transferring its amine group to another molecule?
it undergoes oxidative deamination
oxidative deamination
process that removes hydrogens and an amino group
oxidative deamination where does it occur
glutamate travels to liver mitochondria bc free ammonia in cytoplasm is harmful
oxidative deamination step 1
glutamate dehydrogenase takes glutamate to alpha-ketoglutarate
H2O is used
NAD+ goes to NADH
releases free ammonia
where does free ammonia go?
to urea cycle
when would these reactions run in reverse?
if we needed amino acids, such as alanine
what does the cell have to do after the amine group is gone?
metabolize the rest of the amino acid
glucogenic amino acids
serve as substrates to make new glucose
EX: alanine, glycine
ketogenic amino acids
form ketone bodies
EX: leucine, lysine
amino acids that feed into citric acid cycle
used to make ATP in CAC
EX: valine, aspartate
what amino acid is glucogenic, ketogenic, and feeds into citric acid cycle?
phenylalanine
glucogenic amino acids become?
pyruvate or CAC intermediate
can produce glucose under low glucose conditions
ketogenic amino acids become?
ketone bodies when energy is low
when do we degrade proteins/amino acids?
when energy sources are low
higher protein diet requires more…
Vitamin B6 (bc it processes amino groups from proteins)
