B5-061 AA Metabolism Flashcards
calculate nitrogen intake from protein in diet
daily protein (g)/6.25
conditions that necessitate a positive nitrogen balance
3
- pregnancy
- body builder
- a growing child
consuming the correct amount of protein should result in a
zero nitrogen balance
released from muscle due to protein breakdown
alanine
- transports nitrogen
- transfers carbons to the liver for GNG
alanine
the brain can use […] as an alternative to glucose
ketone
what lab values would be elevated as a result of ketone body metabolism due to a low calorie diet?
2
acetoacetate
B hydroxybutyrate
elevated BUN indicates increased […] catabolism
amino acid
9-4-4 rule of thumb for calculating calories from diet
9 fatty acid
4 carbohydrate
4 protein
calories/gram
proteins have [..] calories/gram
4
in fed states, excess AA are converted to
2
glucose
FA
stored in liver
where does the urea cycle occur?
liver
where does AA catabolism occur?
peripheral tissues
what vitamin acts as a coenzyme in transaminase reactions?
B6 (pyridoxal phosphate)
chemical reaction that transfers and amino group to a ketoacid to form new amino acids
transamination
transamination reactions
3
- alanine -> pyruvate
- aspartate -> oxaloacetate
- glutamate -> a-ketogluterate
deamidation + transamination reaction
Asn -> Asp -> oxaloacetate
dehydratase reactions
2
serine -> pyruvate
cysteine -> pyruvate
a-ketogluterate
oxaloacetate
pyruvate
glucogenic or ketogenic?
glucogenic
anthing with Acetyl-CoA cannot be used to make
glucose
carbons that can be used to generate ketone bodies and fat, but not glucose
ketogenic
the two inputs into the urea cycle
glutamate
aspartate
how do we get glutamate for the urea cycle in the starved state?
a-ketoglutarate + alanine –> glutamate
transaminase reaction
a ketoglutarate can be generated from
alanine via pyruvate
how do we get aspartate for the urea cycle in a starved state?
what AA can the liver make, even in a starved state?
3
alanine
aspartate
glutamate
AA that is main focus in the liver during starvation
alanine
AA that is main focus in the kidney during starvation
glutamine
byproduct of glutamine to glucose production found in urine
ammonia
tyrosine is not typically considered an essential amino acid, but is for patients with […]
phenylketouria
cannot make Tyr from Phe
essential amino acids
PVT TIM HALL
Phenylalanine
Valine
Tryptophan
Threonine
Isoleucine
Methionine
Histadine
Arginine
Lysine
Leucine
PVT TIM HALL
excess protein is
catabolized
fat cannot be converted to
sugar
excess fatty acids are stored as
fat
there is […] of carbon from Acetyl CoA to PEP
no net flux
any disruption in the urea cycle will cause
hyperammonia
reduced urea formation
the urea cycle involves enzymes in the
where in the cell
cytosol and mitchondia
BUN and urinary urea nitrogen indicate protein catabolism […] the urea cycle
before or after
after
during starvation, do we expect an increase in BUN or Urinary Urea Nitrogen?
both
nitrogen balance is a simple consideration of nitrogen […] vs nitrogen […]
in
out
a negative nitrogen balance indicates a need to […] protein in the diet
increase
if the nitrogen is removed from alanine the remaining carbon backbone is a
pyruvate
AA made in the urea cycle but still considered essential in the diet
arginine
someone with PKU lacks what enzyme?
phenylalanine hydroxylase
converts Phe to Tyr
a primary site for amino acid catabolism in the well fed state is in the
liver
a [….] amino acid can be catabolized into metabolites used to make lipids
ketogenic
in the starved state, there are high levels of catabolism in the […] that lead to increased levels of […] in the blood
muscle
alanine
transaminase use the […] form of vitamin B6 as a cofactor
pyridoxal phosphate
after a transmaminase removes a nitrogen from an amino acid….
it remains bound to the enzyme until transferred to a different carbon skeleton
modified enzyme state
urea is a product of cleaving the end of
arginine
the two nitrogens of urea are derived from
aspartate and ammonia
blood urea decreases in what disorders?
3 examples
- liver failure
- pregnancy
- urea cycle disorders
